It’s overused. It’s used by some as a blanket insult for someone or something they disagree with.
But it's really not, though. It's used a lot nowadays because the people the term gets applied to keep doing more and more fascist shit!
(Okay, I'll sort of agree that it's "overused" by people on the right -- but that's not because they're confused about what it means; it's because they're deliberately trying to destroy the meaning of the term to deflect from their actual fascist behavior. In fact, arguments like yours only help them do that, so it's time you quit talking now.)
Yet another way the education system has failed that Trump voter: it's not "slander" if it's true.