By Peggy Noonan April 7, 2022 6:48 pm ET [cut] Why can’t we put a strict age limit on using social-media sites: You have to be 18 to join TikTok, Youtube, Instagram? Why not? You’re not allowed to drink at 14 or drive at 12; you can’t vote at 15. Isn’t there a public interest here? Applying such control would empower parents who face “all the other kids are allowed,” with an answer: “Because it’s against the law.” When we know children are being harmed by something, why can’t the state help? In theory this might challenge economic libertarians who...