You can make your own timesink, for example: Try to beat lv90 mobs with 5 people, if you can then try with 4. Have you done all the sidequests? Gotten all the achievements?

Your suggestion is fine until you get to the reward because then instead of being an extra for people with more time it becomes a tedious, monotonous thing for everyone because everyone wants the best. How about a good item that rivals those at the top but has similar stats and a different art design? You can be unique with your different looking equip but not surpass in stats others who can't dedicate their life to a game.