True, but that's for people who are awake; in this case, we're not actually dealing with (sane, rational, critically thinking) individuals, but with statistics. Nobody cares about individuals denying the holocaust or whatever, but when it becomes a movement, or a feeling, or a suspicion in enough people, it becomes a statistically significant trend that can influence politics, elections, votes, etc.

I mean there's tons of anti-intellectualism going on now wrt anti-vaxxers, flat-earthers, corona-deniers, obama-is-a-kenyan-lizard-man, trump-is-immune-to-the-rona, etc. These are rational individuals, they may not be on Facebook or they may, it doesn't really matter because in the end it's a numbers game.