This post is so developmentally disabled.

What point are you trying to bring when you say that their medical meanings are all archaic? At a point, their medical meanings weren't archaic. That's the point. And the point being made here is that language evolves as medical terms devolve into slang and medical professionals decide to co-opt new and more technical/complicated terminology in place of them-- that it's always happened and will continue to happen.

What you're arguing for actually isn't great at all. Not only are you ultimately not going to stop the use of the word, but you're keeping the medical meaning fresh enough so that it's still offensive on that kind of level instead of letting it dull out and lose its meaning beyond "stupid".

My observation on the usage of autism as a synonym for "stupid" and how THAT'S comparatively more insulting is that "autistic" A) refers to someone with a condition that is far more complicated than mental retardation, and B) the word "autism" was made SPECIFICALLY to describe the condition, whereas "retardation" was/is a general use word (albeit somewhat high-tier) that just happens to have made its way into medical terminology. Not only that, but "autistic" as an insult isn't used much outside of 4chan, so there's the association factor.