I think the idea is to highlight the overwhelming encroaching darkness of the D&D core world.
I mean if you're in a PoL setting, then there SHOULd be an overwhelming amount of evil, and even those that aren't should probably be unaligned. Good would just find it really hard to survive. Evil is winning in a PoL setting.
No, the idea is that you don't need things you don't fight. (What I call Diablo world design. If it moves, kill it).