Werewolf works because the role variety makes for a strategic deduction game.

Among Us works even though it only has crewmates and impostors because you have tasks designed to isolate crewmates, and impostors have to physically find an opportunity to kill them.

Traitors has no roles, yet traitors kill at night like werewolves. The tasks are irrelevant to the deduction game. It just becomes a personality based guessing game where people latch onto shit like "she didn't drink when we all toasted omg she is sus" because there's no method of investigation.