I'd say more generally that the online advertising (or attention, if you like) industry has massive negative externalities that they are trying to downplay and not take responsibility for.
Imho advertising is a meme that is at odds with humanity (meme as in the original definition).
People worry about ai operating in software, this is an ai that has been running in the collective wetware of humans for some time that is significantly hindering us.
If researchers can produce a result that convinces the powers that be that facebook is a mental health issue they can produce a result that gaming or violent movies or maybe something you indulge is a mental health issue.
The new tobacco industry...of decades ago. A long time ago we banned advertising smoking to children (or at least, tried to) but the beforetimes of that decision were rough. Kids commercials for smoking, toy cigarettes, etc. Facebook is actively marketing to youth today just like tobacco did decades ago, indeed.
It's a great analogy because it also works well for adults: we're free to use the product/service, we have our freedom! Even if it slowly (or quickly) kills us.
When I was a kid in the sixties I got chock-like candy cigarettes in my Christmas stocking, and for Halloween. I remember some were a bit powdery and you could blow on them and simulate smoke.
Facebook seems to really have become the whipping boy, despite their falling relevance. Imagine what these depression studies would look like if you did Reddit or 4chan. They get it no matter what they do too. Fail to stop the spread of misinformation in 2016? Come before Congress. Do too much censoring in 2020? Time to break up big tech.