There's generally not all that much point to rollback-style netcode in first person shooters, because you can just run asynchronously and do client-side prediction. If the prediction was wrong, it doesn't matter that much: you might have missed a shot and they're not quite where you expected they were. In fighting games, that's completely infeasible, because each player's actions are completely determined by the previous ones: either I hit you, and I'm going to continue into a combo that's very timing specific, comparatively, or you blocked the hit, and I'm doing something completely different.