It's definitely not just kids. Social media is a lot like meth, we should at a bare minimum stop giving it to kids as soon as possible. And then come to realise it's bad for everyone and should be wound back.
Their argument would be, "If meth is a negative externality, we should just tax it instead of banning it in stores for kids to buy." Kids may die, but I'm sure with all that extra state revenue we'll get a nice park or museum or kickback to Tesla or something.