It's true. We tried. I was there, Gandalf. That's what South Park was for, that's what "ironic racism" was for. We were trying to defang it by making it the butt of the joke. We thought everyone was laughing with us - it's funny! To think that anyone could REALLY be racist etc, in the enlightened year of 2000! Characters saying bigoted things was HILARIOUS because who actually thinks like that?? It was a joke! We were making bigots, the mere existence of bigots, into the joke!
And the fascists snuck in right under our noses, and by the time we realized they weren't laughing for the same reason we were, we had Nazis again. Right out in the open. And we'd emboldened them.
(And yeah. For a not-insignificant number of people, what started as "haha, I'm saying this ironically because nobody actually believes this" turned into "okay but maybe they have a point." Because saying something over and over, immersing yourself in that mindset, regardless of the reason, really does put the ideas in your brain. And unless you're very careful and very self-aware, the thoughts will feel like they're coming from you. Ask me how I know!)