A game is only as consistent and as real as the DM and players choose to make it. Which means that what the books actually doesn't matter unless you prefer games that railroad you.
Ravenloft is a game of gothic horror. People are horrible to each other in that game because it's a game of gothic horror, not because of verisimilitude.
And you can always choose to add as many horrible things into a game as you want. Many GMs manage to do that just fine, and a lot of their stories end up on places like r/rpghorrorstories. Because most of the time, it's done badly by people who include bigotry, claiming it's for "historical" reasons but it's actually so they can be jerks.
And quite frankly, I don't want to play in a fantasy setting where I personally would be discriminated against.