There’s a clear campaign against the mentally ill with the global rise of fascism. Lots of it shows up in anti homeless rhetoric, but you can see it in the MAHA and anti vaccination movements.
There’s no reason to use the word “r-tarded” to describe someone. As someone who’s worked with the intellectually challenged, it’s an insult to them to compare them with people who are willfully ignorant.
Historical context matters.
N igger came from the word Negro which just means black, but slavery and abuse of black people has changed the context of the word.
Dumb and negative iq do not have the same historical context as R etard.
“IQ” is most literally where it came from. Together with “moron”, “imbecile”, “idiot”
Since we all agree that IQ is not an actual quantification of intelligence those words are now used as means to attempt to offend someone, without relation to their medical history or mental aptitude.