Another example Carlin provides is "cripple". It can be used as both an adjective and as a verb and concisely describes the situation. It's entirely neutral and free of euphemism.
The term turned negative because it represented something that no one wanted to be associated with. Even if you were to use the phrase "unicorn-blessed" in the same context, over time, it could also develop a negative connotation. It's not the terminology that's a problem, but the situation it describes.
"Idiot", "moron", and "imbecile" used to be medical terms.
Today, one often hears "He is special needs" said by people who think they are being politically correct. But that's awfully wrong. He might have special needs, but he is not needs. He is a person. To me, that's a lot more dehumanizing than saying "retarded".
Then they'll say "but you know what I mean". That's the point, exactly.
The ultimate culmination being certain subreddits where the banned "retarded" has been replaced by the homonym "regarded", such that referring to someone as "highly regarded" is understood to mean the former, not the latter.
At some point we may collectively realize that controlling language in such a way is impossible. People will just find alternative ways to express exactly the same sentiment.
It'll also get you banned pretty fast in the majority of subreddits, despite the fact that very few people today (and even fewer who use reddit) were ever legitimately referred to as retarded back in the day.
I was called it in both senses of the word and I think that was extremely common for people of a certain generation. I saw the full time special ed getting called that more than occasionally. There were all sorts of popular memes like “arguing on the internet is like winning the special olympics…”
What do you know? The biggest thing I noticed after “retard” fell out of favour is more specific insults like “autist” became more prevalent and I’d say this rotation of the euphemism treadmill has only made stigma worse for certain groups because “retard” was used as such a catch-all that the stigma of it didn’t really seem to stick to people much.
As for banning slurs from Reddit, irrespective of slurs should be banned for the good of those being slurred, they cause derails and are magnets for reports.
I have heard the term "differently abled" kicked around, which completely buries the actual issue. As a "differently abled" person, I will say I don't need to go hiding my handicap, I'd much rather someone figure out to help me adapt better or just fix it, rather than hiding it. I know I have a problem, I have it all day every day. Why are people who don't have my problems so concerned about just saying it out loud?
Invalid is derived from Latin with validus meaning "strong" or "in order". The German and Dutch uses of the word are derived directly from invalidus meaning ~"weak" (maybe via French), while the English word (as its mostly used) is an English(!) negation of "valid", which leans on the "in order" part to get to "inappropriate" or "not correct".
'Invalid' (a weak person) is also pronounced with an 'ə' (in-vuh-lid) in English, whereas 'Invalid' (a improper thing) is pronounced with an 'a' (in-va-lid).
At some point, that was no longer acceptable. The correct term to use became "invalid".
So it was better to say "that person is invalid" than "that person is handicapped".