People calling each other "autists" is a WallStreetBets practice, from Reddit. It's not a thing on 4chan, not even on the interesting place that is /biz/.
4channers would use the "friend"-word as a neutral term (oldfriends, newfriends, etc), or less often "schizo" as an insult, but not autist.
Don't ask me why I'm taking the time to type all of this out, or who cares. Slow news day.
The first time I came across the use of “autist” as a semipejorative term of endearment was on IRC in the late 1990s warez scene, around the same time as the concept of neurodivergence was gaining traction.
I suspect the term has deeper roots than most people realize.
I remember it being used as a synonym for “obsessed perhaps a bit too much” even in the 90s, probably from the idea that if you had autism you would be amazingly brilliant in some tiny subsection of knowledge, like LEGO manufacturing differences.
