I remember watching people raid in Cata with me during DS, I just felt pity for people messing up on easy strats. The first time I ran DS, I quickly read up on the strats for bosses and I didn't make one mistake, you know why? Because it was pitiful but others who had ran it many times had trouble following them. First time I ran HC DS, my guild could't get the first boss down because someone kept making the same mistake over and over again, not once did I fuck up and it was my first time. Some people just suck at raiding and don't realize it, WoW really isn't that hard if you think about it but it's the same as LoL, if your team sucks super hard then it gets even harder to carry them.