Originally Posted by
Baron of Hyrule
Quite the opposite in fact, the undead keep the tasty souls the daemons and dark gods feast on chained to the physical world and stop them from going to the other side of the immaterium/afterlife where daemons can get at them if the god of Death doesn't safely collect them first.
Death is also anathema to the dark gods as well.
Khorne, God of rage and blood. Undead lack both.
Slaanesh, God of pleasure and excess. Corpses make poor bed-fellows.
Nurgle, God of rot and rebirth. The dead ensure there's no life left for his plagues and stop the natural cycle of birth and decay.
Tzeentch, God of magic and change. The dead desire nothing to change or move forward, everything remains stagnant.
The dark gods are alright with ending the world (there's more out there) but while it exists as a living, breathing thing it let's them have fun corrupting it and feasting on the souls and emotions it produces. Undead stops all that cold.