Good thread.
There are disabled people in the future.
The only reason you wouldn’t see them is if that society has gone full steam ahead on eugenics and they’re unable to live freely or be accommodated in public.
I have a friend who said, of Starfleet Academy, that this took them out of it - that seeing a person in a wheelchair in the 32nd century seemed unrealistic, since medicine in Star Trek "should be able to cure whatever was wrong with them."
That's not the case, for any number of possible reasons.