guy on the bottom of the dps meter but stuff dying? no-one gives a shit even if the guy is basically useless/afk, tank playing badly? always noticeable thats the issue with LFR.
in normal/heroic everyone is required to perform, but in LFR only tanks a couple of healers and a few dps are needed, the other half can be failing hard and still get a kill. so tanks generally need to play much better than other specs, which puts a lot more pressure on them and most people don't like that.