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.
People aren’t upset about the word. They’re upset with the people using the word. Telling people to not use the word like that is how they’re “directing that hate.” People are already doing the thing you’re saying they should do.