Even the parents that have degrees and jobs in tech have trouble keeping ahead of all this stuff, because there is far more money and manpower put behind making these products as abusive as possible. Sure, I'd like everyone to be as knowledgeable as us on the subject, but that's not practical. Social signaling has a place for broader society even if it ends up hitting people it won't affect.
Parents are only one side of the equation, with the other being the social media companies themselves. These laws make it so they have to stop offering their services to children, just like I would expect laws to prevent a corner store from selling tobacco or alcohol to minors.