So, we're just going to pretend that language doesn't evolve because it justifies your bias?
People didn't put their foot down when the meaning of those words began to shift, and now they mean something entirely different. In our more socially and culturally aware culture, we as a people understand nuance and are generally educated enough to see what's happening. We have by and large decided that it's a bad thing to continue normalizing attacking the mentally disabled.
Fuck off with your pseudo-intellectual defense of toxic, dehumanizing culture. Words mean things. The things they mean can change. Those ones, in a less educated and accepting time, did. The ones we have now have not. Your attempt to dismiss that is genuinely hateful.