Newsflash: You dont need a tank to clear most dungeons. Tanks arent special. A good tank makes the run easier and cleaner, a bad tank is a complete detriment. If the healer and dps(mostly the healer) say youre doing it wrong, then you are doing it wrong. And read what Micah wrote there - they arent asking you to "pick up after them", theyre telling you they will leave you behind and let you die if you dont keep up. Im normally a DPS. Given the choice of following the slow tank or the fast healer, im with the healer - theyre the one who'll be keeping me alive after all.