tl:dr correlation between them all getting mobile phones and facebook. Perhaps because of the need to reduce it to six paragraphs, it is a very unconvincing piece.
Look at TV. Of course TV has many positives, but it's also another factor in people (at least Americans) becoming much more sedentary over the past 6-7 decades, which has been a large factor in the US obesity epidemic. It's a mistake to dismiss the negatives of TV just because we've gotten used to the fact that nearly everyone is so fat.
Similarly, with social media, forget about teenagers, as I think many people are able to see the huge negative effect it has on their own lives. The fact that we're becoming a society that constantly compares ourselves to the idealized versions of other people shouldn't allow us to dismiss the obvious negatives of those comparisons.
> The fact that we're becoming a society that constantly compares ourselves to the idealized versions of other people shouldn't allow us to dismiss the obvious negatives of those comparisons
I think social media is actually a step up here - the time spent comparing ourselves to idealized versions of our friends is the time not spent comparing ourselves to the apparent presence of all those celebrities and rich people, which was a constant of the previous century. Mass media broke the availability heuristic; the generic dysrationalia it caused in people is clearly visible. Which would be a kind of tech negative I'm not denying.
Nonetheless, just because people have been saying "the world's going down the shitter" for a long time, doesn't mean it's not.