I think there's a dogmatic, somewhat religious element to psychiatry. Instead of being a "sinner," you're "mentally ill" and/or a "patient." The psychiatrists are the High Priests and Priestesses, and the counselors and therapists are lower level clergy.

You faults, flaws, problems, sins, etc. are coded as "symptoms." The High Priest tells you who you are, and you either accept it (the "diagnosis") and do what The High Priest advises you to do, or you deny it ("denial," "lack of insight"), in which case you're perceived as even sick-er (more flawed, sinful, in need of "help") than before.

I say this as someone who takes meds. The psych drugs help make my life more bearable, but I don't know that I have a specific "brain disease" or what have you. I may or may not need the drugs indefinitely, but I do need them (plus vitamins and such) for the next 3ish years, minimum.