I think since forever, there's for example quite a few teenagers amongst the US Founding Fathers age when signing declaration of independence:

Alexander Hamilton 21 James Monroe 18 Nathan Hale 21 John Marshall 20 Aaron Burr 20 Charles Pinckney 18

We always have and it's how the left has lost young men. Counterculture and much progressivism has always been young men meeting up to consume drugs and engage in pseudointellectual conversation. Each generation had them, the hippies of the 60s, punks of the 80s, beatniks of the 50s. However the counterculture spaces of growth and optimism men created grew to resent and exclude them, and they have been scooped up by the testosterone peddling rage dealers that pull them in by their curiosity and desire to better understand and affect the world and themselves. There they are twisted into being dependent on a guide to get them through the delusional world they then believe in.

I see your point, but Asimov was born in 1920 and Foundation, arguably his greatest work, came out in 1951 when he was 31, the same age numbnuts was. "Barely out of highschool" just doesn't apply and frankly feels like a disingenuous attempt to disparage youth. Age unfortunately has very little to do with stupid opinions.