Change in culture, it used to be socially acceptable for people to drink and drive and not wear their seatbelt. Nowadays, it still happens but not so much. Of course, those two things are very clearly easy to show how they are dangerous and we still haven't managed to get rid of it completely so something similar for kids use of the Internet would be harder to pull off. I think combined with some actual studies into the effects, tighter regulation of social media it might actually work though. In the parenting world there's always something new that you get shunned for doing with your child, maybe one day it could be sticking them in front of an iPad.