halfway through responding i talked myself out of my own opinion on this. language changes and i think "on the spectrum" is coming to the end of it's usefulness. it was helpful for a time but now i only use it at work in the context of "i'm just grasping for language that will make you understand how to communicate with me".
On the spectrum is a helpful middle ground when exploring the topic though. And it was a very helpful middle ground when every discussion of autism seemed to devolve into clinical diagnosis vs awareness that the medical system in most countries is a dumpster fire. getting my son diagnosed took very little effort. when i looked into it for myself 6 yrs ago, the clinician was helpfully blunt with "look unless you need accomodations dont put yourself through this yet. theres one person in this state who can diagnose in adults and it's a 2 yr wait list to start the 1 yr $1200 out of pocket process".
a friend got her offical diagnosis about 6 months ago and the process has by her description, improved and shortened significantly. so i may explore that again. at this point outside work i just use autist/autism, but at work i still use spectrum. I do agree the language is aging out of broad usefullness, but i don't believe it's something i'll be bothered by for a long while still. i get your frustration with it. I think we're in that be kind and let people use the language they're comfortable with period for the spectrum. it may die off or it may become elder millenials term for ourselves as aspie has for some genxers who grew up before the spectrum entered the dms5.
im in 4b and it's doing that 60 degree temp change in a day thing. snows then melts, then snows then melts. throwing down native stuff thats been in cold storage right now and reminding myself the warmth is a lie.