But McD did change how they advertise to children. We can limit the harmful practices of social media platforms without banning them.
https://www.businessinsider.com/mcdonalds-told-to-change-ads...
"Research has shown that young children—younger than 8 years—are cognitively and psychologically defenseless against advertising.6–9 They do not understand the notion of intent to sell and frequently accept advertising claims at face value.10 In fact, in the late 1970s, the Federal Trade Commission (FTC) held hearings, reviewed the existing research, and came to the conclusion that it was unfair and deceptive to advertise to children younger than 6 years.11 What kept the FTC from banning such ads was that it was thought to be impractical to implement such a ban.11 However, some Western countries have done exactly that: Sweden and Norway forbid all advertising directed at children younger than 12 years, Greece bans toy advertising until after 10 pm, and Denmark and Belgium severely restrict advertising aimed at children."
https://publications.aap.org/pediatrics/article/118/6/2563/6...
This kind of advertising bypasses parents and creates desire in kids. You might not be able to control what your kid does at a friend's house or at school. Parents can't do it all and so society needs to support parents. Right now social media is setup against parents, we can change that.