As far as I can tell, there isn't a clear consensus on the precise causes underlying depression. It's challenging to treat causes when you lack a mechanistic understanding. So, yes, they've developed treatment protocols that use the tools they have available that sometimes work.

I don't think anybody considers this ideal, but many consider it preferable to no ability to treat at all. A world in which a deeper understanding of fundamentals enabled full treatment would be best for everyone.

It's not like nobody is trying! But setting a bone doesn't require a deep understanding of how bone knitting happens, and therefore comes well before.