People understimate how much social skills and being comfortable around other people can atrophy with these unnatural, previously impossible, modern lifestyles we've created. Historically, especially in our paleolithic setting, you'd be outside and around people like your HG band 24/7 and become acclimated to and, frankly, thrive in that alongside consuming more nutrient dense, less toxic foods that could properly fuel your mental and hormonal vigor.
Nowadays we have created far too many draining and inferior alternatives to this. Don't go out and talk to people. Just sit in your room and chat with people thousands of kilometers away via scribbles on the internet rather than face to face conversations that hone your ability to pick up on and use social cues to your advantage. Don't get a partner. Just drain all your vigor and horniness on p0rn. All while eating nutrient deficient kibble diets. The mind becomes comfortable in this state and going out socializing, building real bonds, having real ambition and challenging yourself becomes too daunting and people convince themselves they're "introverts" and can even develop all sorts of degenerate misanthropic views. It's a shitshow and not autism.
Legitimate autism is becoming more common, though. Seems to be in part due to compromised gut micorbiomes.