It most definitely does not. I used to think it did too because it's my normal. But it turns out that most people manage to get on with life just fine on a consistent basis. Perhaps you have children in mind? But this applies to adults too.
> More research means scientists working towards defining physiological underpinnings, which would lead to more scientific diagnosis criteria (e.g. genomic markers, fMRI/DRI markers, etc.). And if they are found to not have those characteristics, well, what does that mean for them? Does it mean their issues aren't real? Of course not. But it certainly doesn't make sense to call them Autistic. Their disorder should be coined a different name.
I'm definitely in agreement with you that more research is called for and should be encouraged as much as possible.
My strong suspicion is that "mild" and "severe" autism (and quite possibly related conditions like ADHD) will turn out to have to have a common physiological basis. I guess this belief (as lacking in evidence as we are at this point) is partly why I think it does make sense to classify everyone under the label "Autism".