I remember as a kid there was a Youtuber I watched who talked about how growing up diagnosed with a mental disability, every now and then people would come up with a new euphemism for those labeled as being atypical, and kids would just find a way to make fun of that. I remember as a kid we’d call each other “special” all the time in a very derogatory way. For me personally it honestly has a much more negative connotation than “retarded”, because we never really called the kids in special education retarded. It was something we called each other.
As a linguist I tend to take the position that words are vessels for concepts. I treat certain words with respect because of how they affect other people, but ultimately meaning is determined by what everyone collaboratively decides it is. Some social justice people take a hardline view on what’s called the Sapir-Whorf hypothesis, which postulates that the language we use changes how we think. I took a whole class on it in college and in my opinion the data only suggests a very weak effect if any. If people are hateful then they’ll find ways to express it.
That being said, I find it very difficult to talk about cognitive disabilities. One of my closest friends is autistic, and I feel like calling him disabled is pretty nonsense and if anything it’s more so that society fails to accommodate his way of thinking. I also know that there are also people labeled as autistic who require serious assistance and may not be able to live independently. So it’s like if one person has depression and ADD, one has high-functioning autism, another has a TBI, and somebody has severe brain damage that prevents them from taking care of themselves almost entirely, do all these people have a “cognitive disability”? Do they all belong in the same category? Is it healthy to think about somebody who physically can’t walk and someone who thinks more easily in concrete terms than abstract ones in the same way? It’s a discourse I have a lot of trouble engaging in.