Observation:
Many disabilities (no matter what the cause) are not apparent to a casual observer.
We are so fortunate that many things that were untreatable in the past are now more controllable - examples: AIDS, diabetes, some cancers
I think most of us are quite willing to accept treatment for what we consider "physical" problems. There are still stigmas associated with some physical problems - STD's, for one category.
Many of us were brought up in a "pull yourself out of your funk " mindset/attitude for anything that is/was considered "mental" or "emotional."
As has been mentioned - why do (most of us) accept treatment for a "physical" problem such as diabetes - which as far as I know is not curable - only more or less controllable - with little or no comment for ourselves or others?
But when it comes to something that is considered to be "emotional" or "mental" - many of us think it can be "cured" or "helped" by changing one's attitude.
Attitude DOES count - but if the mechanism/organism is malfunctioning, it has to get fixed, if possible, or at least tuned up so it will run better.
A "good attitude" doesn't make fix the flat tire. (Swearing doesn't really help either, but the point is that some sort of intervention is needed to get the show back on the road)