Oh dear. Just wandered in here for the first time. I'll try not to rant. My mentally interesting brain has decided to be awake for no reason so... whee!
The way I interpreted the original question was kind of "Are mental illnesses legitimate disabilities, like physical disabilities are, or are they just something people need to get over & shut up about?" It may not have been intended that way, but I've had very similar questions turn into that exact discussion on several occasions. So, I'm just going to answer with that in mind.
I figure a disability is anything that prevents you from taking care of the basic necessities of life, or requires you to have assistance to do so. I mean, the word pretty much defines itself. So, a mental illness could be a disability, but wouldn't necessarily have to be.
If your doctor says you have *insert mental illness* but you feel fine & are able to pay the bills & all, I'm certainly not going to insist you're disabled. (And I'll look at you funny if you tell me you are.)
On the other hand, my situation. I'm unable to work consistently enough to support myself due to Bipolar Disorder. I live on Social Security/SSI at present. That's not a situation I want to remain permanent. I don't just sit around doing nothing. I do as much as I can. I'm working with my doctor on finding better medication. But, yeah, that is a disabling condition for me at the moment. I mostly can't stand PC stuff, but there's the whole person-first language idea where someone is "a person with a disability" rather than just "disabled." I don't necessarily say it that way, because it annoys me, but that's closer to how I think of myself. It's one aspect of me, not the defining aspect.
(Here's an interesting question... There have been times medications were working well for me & I was able to work steadily, etc. Does that make me non-disabled at that time? I still have the same chronic condition which could re-occur... Even with medication that's working, sometimes it just craps out or develops side effects, etc. So, would I be not-currently-but-pote ntially-disabled? Just an odd thought that came to mind...)
I also have Asperger's Syndrome. Technically, it's a developmental/learning disability, I believe. But, I don't really consider it a disability exactly. More just a differently built brain that can occasionally cause difficulty in a world that's built for the average/typical brain. *shrug* Yeah, it probably would have helped me to have some "Special Ed." as a kid because I learn differently & so forth, but as an adult it's mostly just frequent quirkiness & occasional stuff I have to work around. But it's stuff I can work around, so it's not disabling to me.
Of course someone else with the same two conditions could feel totally the opposite. It's a very individual & not-always-logical thing.