The proof is in playing WoW.
When I see toxicity in the game, it’s because you have 2 players how have completely different sets of goals, objectives and expectations clash in the game.
By opening up variety in the game, you’re creating more expectations and making a more volatile environment for toxicity to appear.
I think people tend to blame Toxicity on a certain type of players. I don’t think that is true, it comes because people have different expectations.