A few days ago, Utah became the first state to pass a law prohibiting social media services from allowing users under 18 to have accounts without the explicit consent of a parent or guardian. The move, by Republican officials, is intended to address what they describe as a mental health crisis among American teenagers as well as to protect younger users from bullying and child sexual exploitation.The technology reporter Natasha Singer explains the measure, and why it could be a sign of where the country is headed. Guest: Natasha Singer, who writes about technology, business and society for The New York Times.