> ASD is characterized by an ability to focus intently on an area of special interest, developing an unusually detailed level of knowledge of that topic.

However, this is not true. It doesn't apply to all people with ASD. I volunteered with adults with ASD about ten years ago. One person in the group really had a special interest fixation (a person), but he didn't know more than the average person would know after reading a single biography. He was barely able to read or remember complex facts, so I don't think he had the ability to develop an unusually detailed level of knowledge of that topic or any other. The rest didn't have any memorable interests, but I guess it's also possible that it wasn't cultivated in them.

It's also true that none of the symptoms of autism apply universally.

I'm good friends with an autistic man, he's got a special interest for a certain branch of mathematics and swing dance. He's also great with regards to social interaction, he's seemed to keep close connections with every person he comes across when he's traveled.

There's a saying that "if you've met one person with autism, you've met one person with autism", symptoms present differently in everyone and they're highly responsive to environment. As a trend I'd say special interests are probably a decent contender for a hallmark, probably along with language difficulty and eye contact avoidance.

The negative characteristics don't apply to everyone with ASD either.

Even more neutral would be to call it Autism Spectrum or Autism Spectrum Condition, not "Disorder".

"Disorder" is a medical term for "badness", especially weird to apply to a condition that is notable for its extreme mental... orderliness.

I never understood autism to be noted for extreme orderliness in all cases. Orderliness from what I understand is just one of multiple possible symptoms that, collectively, are termed as autism.

(You can be extremely orderly and not have autism, for example, if you had Obsessive Compulsive Personality Disorder which is different from the more familiar OCD.)

The thing is, while there may be a broader thing for which “Autism Spectrum Condition” is the most accurate label, modern psychiatry can only diagnose a disorder, and that's not just an arbitrary artifact of naming. We don't have the understanding of the mechanics beneath most psychological conditions, including Autism, to diagnose them other than by the combination of social dysfunction and accompanying factors. To the extent that there is an Autism or Autism-like-condition which is not a “badness” in the concrete conditions in which it is experienced it is outside the scope of what we can meaningfully discern.

> "Disorder" is a medical term for "badness", especially weird to apply to a condition that is notable for its extreme mental... orderliness.

I don't see anything weird about that; are you suggesting that there is no extreme of inflexible attachment to order which would be ever be bad?

Autism is understood to be a neurodevelopmental condition rather than a psychiatric one. This would make sense given sensory differences are common and that autism has comorbidity with prosapognosia.