The fact was that, as droves of demon kings had noticed, there was a limit to what you could do to a soul with, e.g., red-hot tweezers, because even fairly evil and corrupt souls were bright enough to realize that since they didn't have the concomitant body and nerve endings attached to them there was no real reason, other than force of habit, why they should suffer excruciating agony. So they didn't. Demons went on doing it anyway, because numb and mindless stupidity is part of what being a demon is all about, but since no one was suffering they didn't enjoy it much either and the whole thing was pointless. Centuries and centuries of pointlessness.