Back in the 00s or earlier, a lot of people said the r-slur basically as a way of saying "dumb" with emphasis. There wasn't always the connotation of an edge to it, or a direct understanding that you were demeaning people with intellectual disabilities. Even when it was directly mocking those people, you hadn't had an extended period of mainstream reflection on punching up/punching down, or on how fucked up mainstream language can be (e.g., the former name of the Washington Commanders).

But all those cats are out of the bag now. People who say that slur today are at best trying to be edgy, and are at worst consciously being mean. The edginess only kind of works -- everyone knows you weren't saying this a few years ago, so how edgy are you, really? I'm not even sure it works well anymore as performative meanness, because the whole idea of "we're bringing this back" so strongly emphasizes how uncreative it is.