well, okay, then we can say that a lot of people diagnosed with schizophrenia now, even if the concept of schizophrenia is not viable, do have biological disease(s) that cause psychosis alongside what we now call the negative symptoms of schizophrenia. I'm fine with that claim.

it's very different than the common anti-psychiatry claim that the schizophrenia diagnosis is a social construction that gets applied to healthy people who violate social norms.