There was a great Philosophy Bites podcast that talked about the high comorbidity of mental disorders. This one, I think:
https://philosophybites.com/2016/01/steven-hyman-on-categori...The point that stuck with me is that, as you say, the high comorbidity is strong evidence that we have a bad model of the situation. Part of that for me is the medicalization of deviance.
As an example, I saw a bit on Twitter from an autism researcher who was sitting in on a young girl getting tested for autism. She was shown an animation of triangles moving around in a way that neurotypicals would anthropomorphize: https://twitter.com/DrRubySapphire/status/123278780736346112...
She described how the triangles moved instead of humanizing them. She recognized that they looked like they were playing, but knew that triangles didn't have minds. That was marked as a failure, a sign of sickness. Not because she was wrong, but because she was different from the norm.
I think a lot about the world where we just accept that there are a bunch of different kinds of people and stop trying to fit them all into one mold. Where we make the world work for all of them, not just the "normal" ones (which, historically, seems to mean straight, white, moneyed, neurotypical men of a particular body type).