I think it's possible for a kid to be just fine in all important senses, but still need some extra help paying attention to and relating to peers. Autism is not a yes-or-no question where kids are either badly disabled or not.
Even a person with almost-autism (say 95th percentile on autistic-like traits) could probably stand some extra tutoring in the area of peer interaction, just as a kid on the 95th percentile of trouble with reading could probably use some extra tutoring on reading.
Did I turn out fine without a diagnosis of autism? Sure. Would I have benefited from some of the extra help our son is getting? I really think so, that's why we're getting it for him.
For purposes of qualifying for accommodations or disability payments, society wants to put people in the "broken" or "not broken" buckets, and some professionals may still want to define autism as "disabled enough to fail at daily living."
But for purposes of understanding ourselves and our children, and for research purposes, it's much more useful to recognize shades of gray - and that understanding of autistic traits may tell us useful things, even when they are not disabling.
Great post, and I really agree with all of this. My DD9 is a pretty fascinating case study. While not hyperlexic (she didn't read till almost 5, though she became a very good reader right away), she possessed many highly unusual memory skills, was somewhat echolalic, and had some other autism red flags, but many other things about her do not "read" ASD at all. At age 9, she is very socially sought-after but I still see some behavior that reads as "stimming" to me (others do not see it--it's subtle) and there is still a high degree of extreme emotionality and some other traits that suggest ASD. Yet she really is a highly questionable DX and the older she gets, the more we think this would be wrong. However, there are some things she continues to need help with and I do think there are parts of her brain that are "wired" ASD. (For instance, her eye contact is totally normal EXCEPT when she is very upset or in big trouble--at these moments, she has trouble with it and prefers to fidget with something and not look at us. She says this allows her to listen and that if she looks at us, she "can't think." Otherwise, we never notice eye contact problems. This is a perfect example of her "gray area" stuff.)She has sensory quirks for sure. BTW, though, she was a very EARLY talker, speaking in full paragraphs at 18 months, but with strange syntax and pronouns all reversed.
