Podcast Summary: AdExchanger Talks – "Addressing Addressability, With ID5 CEO Mathieu Roche"

Date: September 2, 2025
Host: Allison Schiff
Guest: Mathieu Roche, CEO & Co-Founder, ID5

Overview

In this engaging and candid episode, Allison Schiff interviews Mathieu Roche, CEO of the alternative identity provider ID5. Their deep-dive covers the evolving landscape of digital identity and addressability in advertising, including the ups and downs of the third-party cookie saga, strategies for future-proofing ad tech in a fragmented world, the promise and limits of probabilistic identity, and the emergence of "adaptive identity." Roche offers honest, often humorous, and sometimes provocative takes on industry inertia, regulatory challenges, artificial intelligence, and the rush to contextual and alternative identifiers.

Key Discussion Points & Insights

1. Personal Introduction & Origin Story

• Opening Personal Note

  • Roche shared he had no children at 30 and three at 31, including twins—likening the start of ID5 to raising another child (02:00).

• Ad Tech Journey

  • Roche’s trajectory from MBA in Atlanta to ad tech investing and analytics in France, riding the tech "buzzword" waves from banner ads through to agency trading desks, and finally to the founding of ID5 in 2017 (03:30–05:56).
  • “I lasted all of six months in this boring consulting job and then joined an early stage investment fund…started doing investment in early stage companies that were all at the time pretty bubble burst Internet companies. And one of the early investments we did was in a marketing software company doing audience measurement analytics.” (03:45)

2. The Rationale Behind ID5 and the ‘Identity Crisis’

• Early Recognition of Third-Party Cookie Issues

  • Founders saw three core problems: signal loss, data privacy, and performance.
  • The true spark: solving infrastructure and compliance for the open internet, more than the then-nascent cookie deprecation fears (06:57–09:11).
  • “Advertising works better if you can recognize who you advertise to. Right? Plain and simple. And also enabling compliance for the whole ecosystem.” (08:40)

• Performance & Compliance First, Then Cookie Deprecation

  • "The main arguments and the main reason for launching ID5 was we need a better infrastructure for the open Internet and we need something that is actually compliant with upcoming regulations. Those were the two drivers." (08:00)

3. Google’s Cookie Saga: Drama, Delays, and Industry Impact

• Reacting to Google’s Flip-Flops

  • Despite Google’s shifts, the underlying need for better identity solutions hasn’t changed (09:44–12:54).
  • Roche notes the July 2023 decision (ask for user permission vs. deprecate unilaterally) was “the real nail in the coffin.” (09:44)
  • The eventual "about-face" in 2024 was anticlimactic, after so much uncertainty (09:44–12:54).
  • Memorable Quote:
    • “It’s been a bit of a nothing burger, a lot of waste, you know, hours that will never get back.” (11:39)
    • “It’s funny how many nails there were in this coffin and yet third party cookies still live. Isn’t that funny?” – Allison (12:54)

• Industry Consequences

  • Shifted focus, but didn’t end the addressability problem—fragmentation and technical/legal challenges persist (12:54).

4. Should Google Have Pulled a ‘Safari’?

• Delayed Deprecation and Industry Apathy
  • Roche: the availability of cookies lets industry players avoid “the tough decisions” (14:15).
  • “There’s a real difficulty making this industry move because they have this crutch that they can still kind of lean on... it works up to 50% of the time.” (14:15)
  • Ad tech has relied on "a band-aid on a wooden leg":
    • “It feels like it’s an answer. It’s a very bad answer, but it feels like an answer.” (15:48)
• Result: False Comfort & Missed Opportunity
  • Many shortcuts, snake oil solutions, and confusion—Roche estimates the good-to-bad impact as 30% positive, 70% negative (17:20).

5. Are Alternative IDs Really Being Used?

• Progress on Adoption
  • While alternative IDs (like ID5) are now present in more transactions than third-party cookies, few DSPs leverage the entire bidstream for non-cookie IDs due to entrenched legacy algorithms (20:07–24:58).
  • Roche’s Analogy: “It would be like, oh, I would like the brand of the tires on my car to be this brand or that brand. No, I buy a car, I expect the car to take me from A to B… Identity is a means to an end. Nobody buys identity. They buy targeting, they buy optimization, they buy frequency, right?” (22:37)
• Industry Chicken-and-Egg
  • Buyer/seller stalemate—“Spider-Man meme” where both sides wait for the other to act (21:01–24:58).
  • Collective migration is finally underway after years of delays.

6. ID5’s “Adaptive Identity” Positioning

• Concept
  • Not just about replacing cookies: Adaptive identity means building systems that can recognize users across any device or channel by continually clustering and interpreting privacy-compliant signals using machine learning (26:52–30:55).
  • “The number of combinations… is surreal… so only through machine learning and through an algorithmic process are we able to do that.” (28:16)
• Why Adaptivity Matters
  • Adaptivity is needed for legal compliance, technical changes, and scale—"at the speed of AI" (29:35).
• Machine Learning as a Foundation
  • Can improve cross-device resolution, adapt to context, and process the volume (7 billion signals a day) that static methods like cookies can’t reach (28:40–30:55).

7. Probabilistic vs. Deterministic Identity & Privacy

• Balance of Precision and Scale
  • Accuracy is a function of trade-offs between recall (scale) and precision.
  • Deterministic not always better than probabilistic:
    • “JohnDoe@email.com is probably an email address we get 10,000 times a day… if I use that to match IDs across devices or domains, I’m going to be wrong every single time.” (34:55)
• Privacy as a Binary
  • Compliance is about notice and choice, irrespective of whether matching is deterministic or probabilistic (31:34–34:20).
• AI’s Role
  • AI is as good or bad as its training; constant validation and retraining are crucial (37:41).
  • “Perplexity gave me a three paragraph dissertation on Abilify, which is, I believe, a drug for depression…” – Allison, on AI’s unpredictability (37:05).

8. Lightning Round and Hot Takes

Identity Provider & Ad Tech Rapid Fire (38:51–45:28)

• Apple vs. Google on Privacy:
  • “No [Apple’s approach isn’t better].” (39:01)
• How many alt ID providers does the industry need?
  • “I think three to five is where it’s going to land.” (39:15)
• Hashed email IDs sustainable?
  • “Sustainable, yes. Sufficient? No.” (39:27)
• Will identity graphs be obsolete in 5 years?
  • “No, they’ll be more needed than ever.” (39:40)
• Will browser fingerprinting ever be fully gone?
  • “I hope so. Yes, but it’s unlikely.” (39:48)
• On browser fingerprinting transparency
  • “Fingerprinting on its own is not a problem. It’s how you use it, how transparent it is to the publisher and to the user. If you do it non-transparently, …in some countries it’s just plainly illegal… very, very unethical.” (40:17)
• Trend people are ignoring:
  • Measurement (“If you don’t measure, it doesn’t matter.”) (43:02)
• Will GAID be deprecated soon, like cookies?
  • “Yes.” (43:36)
• Trend people are overhyping:
  • “Agentic AI... way too much ink being spent on something mostly slideware.” (43:46)
• Buzzword that makes his skin crawl:
  • “Contextual 2.0.” (44:22)
  • “It feels like contextual all of a sudden was the best thing since sliced bread, as if it was rediscovered…” (44:43)

Memorable and Light-hearted Moments

• “If an alternative identifier is present in the bid stream and no one transacts on it, does it make a sound?” – Allison’s riff on the philosophical "tree in a forest" (18:54)
• On favorite cookie: “I’m a classic chocolate chip cookie guy… if they are my daughter’s, because she’s an amazing patisserie chef.” (46:09)

Notable Quotes

• On Google’s Cookie Saga:
  “It’s been a bit of a nothing burger… a lot of waste, you know, hours that will never get back.” (11:39)
• On Industry Inertia:
  “There’s a real difficulty in making this industry move because they have this crutch that they can still kind of lean on.” (14:15)
• On Measurement:
  “If you don’t measure, it doesn’t matter.” (43:02)
• On Adaptive Identity:
  “No static methods of recognizing users will scale to that level.” (30:50)
• On Contextual 2.0:
  “It feels like contextual all of a sudden was the best thing since sliced bread, as if it was rediscovered… it’s a false resurgence.” (44:43)
• On Privacy & Fingerprinting:
  “If you do it non transparently without properly compensating the publisher and getting the agreement of the user, it’s… very, very unethical.” (41:24)

Key Timestamps for Reference

• 02:00 – Personal/family intro
• 03:30 – Roche’s ad tech origin story
• 06:57 – Why found ID5: performance, compliance, privacy
• 09:44 – On Google’s cookie drama and its real impact
• 11:39 – “Nothing burger” quote on wasted time
• 14:15–15:48 – Band-aid on a wooden leg analogy
• 20:07–24:58 – Alternative IDs adoption and industry inertia
• 26:52–30:55 – Adaptive identity, machine learning
• 31:34–34:20 – AI/probabilistic matching and privacy explained
• 34:55–36:55 – Accuracy vs. scale in identity
• 40:17 – Nuanced take on browser fingerprinting
• 43:02 – Underinvestment in measurement
• 44:22 – Contextual 2.0 buzzword critique
• 46:09 – Chocolate chip as favorite cookie

Overall Tone

The conversation is frank, humorous, and jargon-rich, offering both a historical perspective and grounded predictions about the future. Roche’s answers combine industry critique, optimism for smarter solutions, realism about collective inertia, and a focus on practical privacy compliance.

Closing Sentiment

Although ad tech has spent years chasing the demise of cookies, the true challenge—future-proofing identity with compliance and adaptability—remains. As Roche sums up:
“We need to spend a lot more time on measurement… and adaptive, real-time solutions that respect privacy. No static methods will scale.”

And in the end, when it comes to cookies—at least the edible kind—sometimes classic is best.