As much as I want to agree with the conclusions of this study, I have a hard time believing them. Anecdotally I do feel like social media has weakened a lot of social relationships (although they do persist longer than they would have in the past, so maybe thats a plus). I feel like these relationships have weakened because people have started using their online relations as substitute for their in-person ones. In addition to that, I actually feel more anxious/depressed when I spend more than an hour or so on social media, mainly because of FOMO. There have been multiple times in the last few years where I was sure I was addicted to social media and would get anxiety because of it. During these periods I've had to turn my devices off and leave them at home for extended periods of time to "reset" myself.

Again, all anecdotal, and likely this study was very thorough, these are just my own experiences.