I agree. I am old enough that labelling was not a thing when I was at school otherwise I am sure I would have been placed somewhere in the Spectrum. I was just regarded as difficult but ultimately rewarding (luckily).
I have the ability to concentrate on tasks for long periods of time, amongst other things, but also the handicap of putting off starting them (not an uncommon one, I think). I would have definitely slotted into the weird category socially when I was young but was fine with people who outside observers would have said needed supervision.
I made a conscious decision when in my mid-teens to break away from the kind of fantasy world I was starting to inhabit. I now hold down a very responsible job, literally in charge of peoples lives and lots of highly valuable resources but I retain the high functioning aspect and use it to my advantage completely consciously.
Projecting forward my existence, I could see that society would view me as mentally ill if I progressed much further that way. Several of my friends carried on in that direction and still need regular professional attention decades later. I have to admit the pull of complete geekery, to coin a phrase, was strong and I nearly gave in to it. I still enjoy these kinds of pursuits but they come second to family, job, other people, etc. I am fine now, ha ha ha!