I think the bigger issue currently is we understand so little about the brain. For something like Schizophrenia there is very obviously biological origins - not that environment doesn't have an impact as well, but you're not solving that with behavioral therapy alone. However I think biological psychiatry has sorta thrown the baby out with the bathwater in the way it tries to study these disorders, lumping everyone with psychotic disorders into one basket and doing some one dimensional studies on that.

Since we don't really have a foundational understanding of the brain and these are complex (probably multiple distinct under 1 umbrella) diseases, it's difficult to draw many real conclusions. Unfortunately on the flip side it is rare to see professionals that focus on the human side of things think much about biology. So you get a weird gap where people with fancy biology tools are studying very ill-defined phenomena, and people who work on unpacking the psychological phenomena are entirely ignoring the critical underlying biology. Maybe one day the fields will be better bridged, but research that is currently done isn't really abstracted in a way where it's feasible for the two sides to meaningfully inform each other. Plus there are cultural barriers in place.