Believe it or not, it's very doable to keep dps alive as long as the number of monsters is not so many (3-4 or so, depending on hp and overall damage dealt by monsters). In my experience, even during 3.x, healers go on a sort of super saiyan survival instinct mode when the tank dies. This is because they don't want a complete wipe. If they can gauge that there's a chance a complete wipe can be evaded by healing the surviving dps through the ordeal, they will do it. Otherwise, they'll just suicide so the party can retry properly. While the tank is alive, they know they can dps and just throw out a heal or three so the tank doesn't die; they're in an "idgaf" mode, so to speak.