With autism but really any neurological variation in humans, it's often said but seldom fully grasped that most variations exist as spectra. This is hard for people to reason about because thinking in hard-line categories seems like it's more intuitive to most people. Still, I think it's useful to remember that whether you think of it as difference or disorder, there are always degrees
There are two competing pressures in psychopathology that are essentially incompatible with each other. On the one hand, healthcare administration and especially the nightmare that is the privatized and insurance-driven US healthcare system puts pressure on justifying needs. Since insurance really tries its absolute best to never help you if it can get away with it, people with extreme divergences are incentivized to insist that only the most extreme manifestation of something is real, everyone else is faking it, and that makes them bad. If something starts to be "not a disorder" in the public perception, insurance companies will use this to try to weasel out of providing necessary support.
Basically every point on a given spectrum exists in some living person though. I'm close to someone who probably couldn't get diagnosed with autism as he can speak fluently and mostly take care of himself, as well as socialize among some circles of people, but certain kinds of social pressure just completely break his brain, and on top of that he has pretty extreme and disabling reactions to certain kinds of overstimulation, including reverting to hitting his head on walls, a behavior he had to pretty meticulously train himself not to do. I would definitely describe him as autistic. I think he's a less extreme case than people who are nonverbal. People like him might not need or want or benefit from medical intervention or navigating the other insane bureaucratic nightmare of disability benefits, but also might not be able to function in society. Specifically, I think he'd have been screwed if not for finding circles where people are aware of these traits, structure their social norms to not function as a minefield for people who are like that, and treat him with compassion. This comes from recognition that autistic people exist and may not be completely categorically obvious, and people like him have to push back against gatekeeping "real" disorder because doing that means people bicker about that and accuse you of stealing valor and then conclude it's too much effort to try to understand the nuances and who's allowed to call themselves what, and in this situation, most people will just throw up their hands on understanding and do what comes naturally to them: Exclude and ridicule people they find weird
I think we could solve both of these problems if we provided more paths to success for people without strong social skills, didn't exert so many conformity pressures on people in every context, didn't put amoral paperclip maximizing bean counters in charge of crucial services like healthcare, and didn't have the neoliberal dogma that most people who say they need help are faking it and thus we need to torture people with hoops to jump through if they want any hope of getting it
Mental disorders are real. They're also made up. We choose what differences are salient and how to cluster them. We set a threshold of difference that's adequately disabling because the rules say we need one. We try to see what we have in common with people different from us, and try to describe them and empathize with them. When it's apparent someone is "sort of weird in the vague direction of spaciness" it makes sense to both assume this might be what we call ADHD but milder, and even if you don't think that's literally neurologically true or whatever, we often describe things in directions or by analogy.
I think it's impossible to get this right. I still want to make private insurance illegal. I still think we should do less harm to people for not learning to politic well. I still think that the internet made everyone so obsessed with words that they have holy wars about the true meaning of several of them. Rather than get drawn into them, I think we should solve the problems that make them feel like important battles, because words are at the end of the day mostly just attempts to communicate. Besides, we're many of us programmers here. We all know most names are fungible