"The dead can be spoken to. It involves a long, dangerous process, and there have been those who entered the Underworld to do so. I would not recommend either." The Underworld's motto is "There is no escape," and it does everything it can to keep the shades and the wretches from finding their way to the surface.

For a lot of people to die all at once, Death would be very busy indeed. It's what Thanatos might face when he goes home, after death having ceased the entire time. "It must be crowded, your Farplane."