Said this elsewhere, but when was the last time you heard "idiot" used as a medical term vs "retarded?" I still hear grandmas use the latter to describe disabled people, so it's definitely more offensive to use "retarded" as an insult than it is to use "idiot" considering the current meaning of those two words. "Idiot" isn't still sincerely used to describe a vulnerable population of people, and sometimes "retarded" still is, albeit usually by older folks. That's the difference.

I think you're trying to say they're equivalent, but honestly I'm not sure if I'm understanding the tone of your comment. If you're sincerely decrying people in here justifying insulting others, in general, I'm with you. They seem to be scrambling hard to justify their own shittyness.