While I don't doubt that social media can drive some of these mental health issues, I think most teenagers are simply stressed from the constant work that's necessary for the college admissions process. I'm 24, so I would have been a teenager in 2012, but I didn't have a smartphone until I was 16 or so. My high school experience consisted almost entirely of school, studying, and running (my primary extracurricular).…
-- One flatly refused to leave home despite a lot of pushing from their parents. They are working at the local theater and taking community college courses here and there with no real future plans or goals
-- One also decided to go to CC, with her parent's support this time. She's 21, just got married, and has decided to be a vet tech with the anticipation of being a SAH wife and mother.[0]
-- One went to a top university and had a mental breakdown earlier this year - going back home and almost refusing to get out of bed or eat. Fortunately(?) this happened over a 4 week winter break, and with support from her parents and a prescription for anti-depressants she is back in school.
Not very inspiring outcomes. I personally think that the pressure from high school really ended up convincing them that they never wanted to work that hard again.
[0] I don't want to look down on women who wish to become SAHMs, but I think it's terribly short-sighted to make that decision at 21 and give up on pursuing a "real" career.