it becomes a disorder when the person faces "too many" difficulties due to their difference (instead of enjoying the advantages)

and of course there are extreme cases, like the many non-verbal people (who likely wouldn't be able to live alone, their communication is limited to poking at pictures on a board), and the truly end of the spectrum where nothing sort of institutionalization can provide the environment and care necessary for survival

but of course having our society somehow become so narrow allows for the economic efficiency to even have the surplus that then we give to people with these disorders (in the form or care, attention, medical research, and so on)