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.
I never really understood the difference between insults and slurs. Somebody said that slurs target groups of people and imply that just being in the group is bad. That explanation works for ethnic/racial slurs or the ones regarding gender/sexualities.
But to me “retarded” is not specifically tied to a group. It’s not mainly used for people who are disabled or neurodivergent for example. As far as I’m concerned it’s the same as calling someone a moron or incredibly stupid.