But that's the thing, sight and blind can be easily defined.

"Autism" can't, most of the people live undiagnosed, many mask the symptoms unknowingly, specialists can't even tell exactly if someone is autistic or not, many people are misdiagnosed, or diagnosed as neurotypical by some specialists and neurodivergent by others.

I don't think the ratio is that far towards neurotypicals as it was previously believed. I think that, as most things in life, it's a gaussian distribution.