To be clear: I don't think it's an intentional case of "we just want to make people measure up to our idea of normal." But what I've seen happen is more "I'm used to X and not Y. This person is presenting in a mental health practice with Y. Y isn't what I'm used to seeing, so it's a result of the mental illness. Therefore, as part of treating the mental illness, we need to deal with Y." I've seen that happen a lot - for example, I had it with my parents, where mental health professionals would rather believe that I'm paranoid than that an apparently interested loving mother can be quite manipulative and emotionally abusive. Had the same thing happen with the way I dress, even - they're personally disturbed by gothic fashion, so clearly it's a symptom of mental health problems that must be treated.