[Scalestein]

It isn't just social media, it is the combination of social media and smartphones. This makes social media far more pervasive in a teen's life.

See section 6[0] where they discuss how mental health declines correlating with Facebook coming to college campuses and with high speed internet arriving in cities for some evidence.

[0] https://jonathanhaidt.substack.com/p/social-media-mental-ill...