The way to tell MAGA propagandists from real lefitst activists is that propaganda will ignore primaries and local elections. General elections in America are for forming coalitions, not rejecting them.
Anyone making memes telling you not to form a coalition against MAGA is working to further the goals of MAGA.
How would you feel if something you couldn’t change about yourself was used by your peers as an insult? You really don’t see how using the word “retarded” as a stand-in for “stupid” is still an insult to people with mental disabilities? If someone was acting stupid and you said they were acting “like a Chinese person” that’s still insulting to Chinese people even if the person you’re targeting isn’t Chinese.
Also I’m calling shenanigans on “the 1980s definition”. I am the same age as you and I was taught it was cruel to use the word that way back then.