I have never ragequit for any reason. There are runs that are frustrating, but if a run is frustrating I first examine what the problem is and then I try to address it. If I notice mobs are dying slower than I would expect or a tank is having trouble holding hate/taking too much damage (not counting the massive iLevel differences in level 50 dungeons), I check gear, watch actions, give pointers, etc. A player's job is to help others to become better players.