>Of course, this sucks for the disabled
You question the obvious benefits -- the fact that business can't just fire/not hire you for say, a work related injury, or getting injured elsewhere, or being disabled in general, and then you provide absolutely 0 recourse except "Sucks for you bro."
>a disability will impact your ability perform general tasks (and require additional accommodation).
The entire point is _REASONABLE_ accommodation. With reasonable accommodation, most people who suffer from disabilities can do their jobs just fine. Your glasses are _reasonable accommodation_ against you not having 20/20 vision, so is a hearing aid.
Does me having a ?/10 vision corrected to 20/20 (just an example) with glasses affect my performance as far as me being a (software engineer, accountant, construction worker, truck driver, scientist, biologist, doctor, pharmacist, teacher etc.) goes? What about an accountant who uses hearing aid to listen? What about a wheelchair bound software engineer who doesn't really have to move to do their job?
Unless your alternative is just that disabled people should be out on the street starving, worker protections in general are a good thing.