I dont even main the tank role (im a healer) and I've never had much problem with dps pulling aggro, even when they are the ones that dont pay attention to the aggro meter. If someone needs to mark mobs past lv 50 (unless its like a high priority mob like bees or something. Marking those is fine) just to be able to keep hate then I'm sorry but they are not as good a tank as they seem to think they are.