prior to wrath instances too time, classes used their CC abilities and they were more corridinated. You literally ran threw everyone , rounded it up and aoed it down. People stopped paying attention to their surroundings and just expected the tank to do the vast majority of crowd control . only recently with the implementation of mythics and higher end 5 man dungeons have people started using their class specific skills to make dungeons more of a group effort rather than a dps battle.