I think the thing about the word “retard” is that it’s not so much about something being aggravating as it is about something being absolutely stupid. It has these hard consonants that make it sound powerful when it’s said. It’s effective, and it’s really uncomfortable to hear. It’s the fuck of the moron/idiot family of words.

And we’ve got this reality where there’s variability in how smart people are. And then people with developmental delays get tossed into the extreme end of the scale with medical terminology, and so that gives people an easy word to use when someone is acting on the extreme end of “not smart”. And then the word becomes a slur, and then a new word gets coined that’s medical and not a slur, and then it gets co-opted as a slur, and so on.

And it’s not gonna stop, because sometimes you do gotta call out someone for making stupid decisions, especially when their idiocy is causing harm. It’s just we’ve also got assholes around, but those people will insult more than just someone’s brain, they’ll go for anything that hurts.