It seems to me that some of the "high-functioning" / "low-functioning" autism distinction has actually to do with the comorbidity of various other disorders and disabilities; as well as with the quality of schooling and other care. There seem to be a number of autistic folks whose lives are complicated by PTSD from bad psychiatric care, institutionalization, abusive schooling situations, etc. Presumably, if ASD were more common and better understood, these would be less likely.