It's true. This meta-analysis was posted a while back on HN with this key quote:
"In social media research, we focus on “how much social media did a person consume?” and we plan our experiments accordingly... Most don’t even distinguish between platforms, as if Instagram, Facebook, Snapchat, and TikTok are just different kinds of liquor. "
Like I wrote in a comment back then, it's like blaming "computers" or "the internet". Vague to the point of useless.
Well imagine this experiment. You take 100 kids and put them into the animal enclosures at a local zoo. Some are put with sheep, some with birds, some with sharks, and lions and others with elephants. You notice that more of these kids these die than the control group that went to the zoo but outside the animal enclosures. Conclusion: wildlife dangerous. What you cannot conclude certainly is which wildlife is dangerous, there simple weren't enough participating kids. Maybe the reason the kid put with the lion lived is because lions are safe, or maybe it was because the lion was just fed. That would take a follow-up study to find. And what about kangaroos? The zoo didn't even have so we would have to try to extrapolate.
If I'm doing the zoo study with 100 kids, I might turn it in for my 6th grade science project and enjoy my A.
If I'm the Surgeon General of the United States, I'm doing the follow up study. As far as I can tell, that follow up study hasn't been done with kids and social media.