>On one extreme, we have people thinking they're autistic when they're actually just awkward and inexperienced in life

And you know that they're "just" the latter, and not autistic, because? They don't look like the Rain man?

I get the feeling that with a sufficiently advanced understanding of the brain we could attribute every personality trait to a biological explanation, but if someone isn't sufficiently disabled or in need of treatment, is there any benefit to doing so?

The person who possibly is on the lightest side of the autism spectrum has so little in common with the other end that it feels incorrect to label them as the same condition.