We already do this with some slurs, right? We can start enforcing these words, too.
Not calling anyone out, I’ve been guilty of it too. And we don’t have to do it all at once. Like, we can start with these:
Ableist words and alternatives.
Stupid, R€tarded, Idiot(ic), Cretin, or Moron(ic): People say this to imply something, or someone isn't intelligent or worth their time, but the words refer to people with intellectual disabilities. Instead, say that a situation or person is frustrating, ignorant, dense, unpleasant, cheesy, or awful.
Dumb: This word refers to a person who doesn't speak verbally, but people often use it to mean that something or someone isn't intelligent or wise. It's listed separately from stupid and its synonyms because it references a physical disability instead of an intellectual one. Try using any of the non-ableist synonyms like irritating or uncool.
Crazy, Nuts, Mad, Psycho, or Insane: "Wow, that's crazy!" may not seem like a harmful statement, but if you think about someone with a mental health condition hearing that statement, it's easy to realize that it is. So instead of using one of those words, try outrageous, bananas, bizarre, amazing, intense, extreme, overwhelming, or wild.
That said I wouldn't mind spaces being less ableist. Calling out stupidity is often a method to silence marginalized and those that are oppressed. It also makes it so that caring for people is less important than being an Ender kind Isekai who is just so smart he alone knows what is right and lifts up "reasonTM" and uses cold Nazi-eqsue pseudo-science as the ultima ratio (like the Nazi scientist in Strangelove) .
It also ignores that people are diverse, the same person is, too, that person is both in their faculties and circumstances sometimes - not always - able to check stuff (i.e. code switching when talking to people), and the other component is the change in time. All of us have intervals in which we aren't able. Society acts as if you are always either able and useful or not.
Important is still though if you talk to people that share intimate stuff currently not to police them in the wrong situations. If a friend is fired them insulting their boss is good and supporting them is the right call. But there is a difference if they call the boss an asshole, capitalist or use the n-word which ought to be called out.