Who needed a study? We've known this for years, and it was even speculated at the dawn of Friendster, MySpace, etc. Watching a society (the US, for example) slowly say "social media is bad" then continue to use it is like watching a stumbling drunk declare their ability to quit drinking anytime they want.
>>ranger+(OP)
Even intuitive things should be studied. It’s valuable to know the scope and context and magnitude of impact. “X is bad” followed by confabulation, which is how many of these discussions go, is not helpful.