Imagine DPS classes had responsibility

It has been discussed a hundred times on this blog and at many other places that the raid design of World of Warcraft puts a lot of responsibility on the tanks and healers, and much less of it on the damage dealing classes. With the predictable result that people tend to shout at the tanks and healers after a wipe, and then tanks and healers are increasingly hard to find. So what if a game came and reversed that? What if tanking and healing was relatively easy, and fails were predominantly caused by the damage dealers not dealing enough damage per second?