There are depressed people who don't use the internet at all. Your symptoms would just fall into something like "IRL symptoms". I think the the study is trying

There are depressed people who don't use the internet at all. Your symptoms would just fall into something like "IRL symptoms". I think the the study is trying to point out a detection mechanism for depressives who use internet. It wouldn't be a holistic diagnosis. That said I'm not sure corelation and causation in this study. I feel like people can use the internet for "escape" and "entertainment" and still lead perfectly fulfilling lives.