It’s always been a slur to differently abled people. Some grow up and go through life hearing it constantly as a way to shrug them off as disposable or something. It’s a way assholes in society treat them like shit.
What’s gone on recently is offensive cause there are real people who through life being called that and other names as a way to disregard them. Having to hear how it’s been openly used lately isn’t great, but people don’t get it. They think some things are harmless merely cause it doesn’t affect them or someone they care about.