Assumed to be Normal When You're Not
Apparently this scenario is nothing new:
"One of the main reasons that the moron is so dangerous under present condition is that he is not understood; he is assumed to be normal, he is treated like a normal person and is expected to react like a normal person. There is no evidence to prove that the feeble-minded person taken in the beginning, understood and properly treated, becomes vicious, bad or dangerous. On the contrary there is much to prove that he is not vicious; he may be made so by mistreatment but he is not so naturally. A menace to society? Yes when mistreated, when not cared for, when allowed or compelled to bear the burdens of intelligent people."
(Henry Herbert Goddard, Feeble-Mindedness, 1916)
"It is now several years since that this city was excited by the trial before a Master of Lunacy of a young man whose ability to manage his affairs was doubted. ... The jury supported the doctrine of the liberty of the subject, and the poor congenital imbecile was allowed to go his own way to destruction, with the result of becoming speedily bankrupt in fortune, ruined in health, and a scandal to an honored ancestral name."
(John Langdon Down, Mental Affections of Childhood and Youth, 1887)
Of course, there are differences between that idea around the turn of the century, and the current discussion of high-functioning autistics. Firstly, they were discussing people who would presumably (and in Goddard's studies actually did, although he had a higher cutoff for normal IQ) have a below-average IQ, rather than normal-IQ cognitively disabled people. More importantly, these were doctors, not self-advocates, and the help they were proposing was disempowering to those being helped. But the idea that someone who's treated like they're cognitively normal when they aren't can get into trouble as a result - that's nothing new.
* Not that lower-functioning autistics don't have trouble getting services - especially if they break stereotypes in some way. I've heard of autistic facillitated communication users being cut off from services because their IQ scores are too high - even though they're still unable to do many self-care activities or keep themselves safe.