I have an anxiety disorder. Mine's co-morbid with ADHD, but even if it weren't ADHD-like symptoms are well-known secondaries of anxiety and depression. For people like me, gamification helps greatly with incentivizing participation until a habit is built. I have no idea if this particular app would be what'd do it for me, but you're down on the concept in general in a way that doesn't represent my own situation well.

I do hear what you're saying, and nothing replaces social interaction, but I think you're making an assumption about this being a be-all-end-all. Maybe it would be for some, but those are probably the people who wouldn't adequately find in-person on their own anyway. Maybe this gets them far enough to do so, since just being functional enough to get help in the first place is often one of the biggest problems.

On another note, everyone's different. It's one thing to say what works for you, but your social fulfillment will likely be higher if you don't tell everyone else what will and won't work for them.