I think low IQ is stigmatized at least as much as autism...actually worse since so many ASDers stigmatize and "other" fellow ASDers and really anyone with more cognitive differences/impairments or low IQ
...and people don't understand that having intellectual disability (ID) doesn't mean you cannot learn things, make good choices, be indepedent, be insightful, communicate, have talents, have a career -- like any other category of intellectual functioning, ID is a spectrum of many abilities.
Yet people see ID and autism as black and white ( ironic because we are supposed to be the super simplistic black and white thinkers) -- that if you have ID you must be unable to do anything, or at least not anything "normal"
And that if you don't have ID then you cannot possibly have any severe impairment -- anything you truly cannot do...
Both ideas are just wrong.
Having an intellectual disability or autism (or NVLD or ADHD or dyslexia or dyspraxia or dyscalcula or language disability or whatever else) often just means some things are harder for you to learn or to do, or take you longer, or that you need a bit more help than most. There's nothing wrong with that and people shouldn't be written off an unable to do anything at all!
One thing I would like to see become more commone is supported decision making orders -- a better option than guardianship for many who truly are capable of making their own choices but might need help considering all the information or communicating their questions, concerns, and decisions to others.