I haven't researched the topic of social media's effect on young people, but the common sentiment I encounter is that it's generally harmful, or at least capable of harm in a way that is difficult to isolate and manage as a parent.
The people closest to this issue, that is parents, school faculty, and those who study the psychology and health of children/teens, seem to be the most alarmed about the effects of social media.
If that's true, I can understand the need to, as a society, agree we would like to implement some barrier between kids/teens and the social media companies. How that is practically done seems to be the challenge. Clicking a box that say's, in effect, "I totally promise I am old enough." is completely useless for anything other than a thin legal shield.