Honestly, I think the fact that, as the headline says, "it's international" is evidence against what you're saying.

Even though the post only covers the Anglosphere, I'm from Spain and the phenomenon also happens here and is often qouted as worrying (e.g. child and teen suicide trends: https://s.yimg.com/ny/api/res/1.2/OJt9haHrWhKMDEPsTtrj3g--/Y...)

I don't think the Spanish society is especially competitive - no one cares about IQ, just a minority (going into academic sector) cares about GPA, stack rank is not a thing in any company I know here (maybe it exists, but if it does, it would be rare), and income... well, people do care about that, of course, but as they have always done and more out of practical reasons than sheer competitiveness - in fact, many people would rather be a public sector worker with a super stable contract than earn a lot of money with more instability.

And still, our teens are completely messed up. So I think either phones, or social networks, or a combination of both are more likely culprits.