It wasn't well-documented until recently: afaik, it's largely due to Dr Damian Milton that academia takes this idea seriously. Most academic research about abnormal people is just the rampant pseudoscientific speculation of a respected academic, which has become Accepted Truth because it's published in a serious scientific journal.

This has been getting better over the past decade: I think increased access to science is making it easier for the subjects to learn about the "research" and say "hang on, this is nonsense". On the flipside, though, bigots have increasingly been picking the worst theories from the literature and using them as an excuse to do bigoted stuff. (e.g. you still see lots of people claiming that autistic people "have no theory of mind", because they don't understand that ethics are suspended when nobody's looking)