"Take a warm bath" suffers from a lot of the same problems as this study. You can't actually have a blind control group, so there is effectively no control group.

So this is really just 17 people assigned to take a warm bath. The thing about mental illness is that it's really really hard to be sure if something helped. You're brain is the thing that is broken, and your brain knows you are being treated.

I have depression. I've lost count of the things I've tried, and when asked, I have to say "I don't know if this actually helped or if it's just my brain thinking it should have helped."

With depression, studies which are not double-blind are garbage.