In my (admittedly old in Internet years) experience, and the (more recent) experience of people I interact with, schools are microcosms in this regard: two schools may be within the same city, or even the same neighbourhood, but the presence of the social media networks and their relative popularity and use within them can vary hugely.
As an adult looking on my younger sibling’s social media interactions (or what is visible of them, anyway), while also looking back at my own social media interactions in high school and around then, I can tell that there are more or less subtle differences between what social media people from the private or “good” schools use and what is used by people from schools that are looked down upon. Visiting school-age acquaintances in other cities paints an even more different picture.
This isn’t limited to teenagers, of course; social media usage differences by demographics, geography, and occupation are well-documented and somewhat “obvious”. But I feel that teenagers who spend practically all their time at school or interacting with school-related people are particularly insulated that way.
I disagree with @TysonJones below: teenagers today and yesterday are heavily invested in social networks… but you simply forgot that texting, calling, and “real life” interactions are also social networks.
The takeaway from both @Go_Soroush’s and @thatswattsup’s articles is pretty simple, really. There is one social media network that everybody uses, everybody has mostly the same opinion on, and that isn’t going away anytime soon: YouTube.