I don't know - the term "ableist" has certainly spiked in popularity in the last ten years or so, but even in the 90's you'd get a bollocking for throwing around the terms "mong" or "spaz" or "flid" within earshot of a teacher.
I mean, I can see why - I hate the terms myself now. but when you're in single digits of age, it's just used as another derisory term rather than a specific slight at someone's physical or mental development challenges.
It still got you in hot water if you were daft enough to get caught shouting it though.
Nah I was in a pretty small town, semi-rural but not buttfuck-nowhere either.
It certainly wasn't labelled "ableist" then, it was simply "being a little shit" - I only really learned of the term ableism around 10-15 years ago.