Exactly this. A PoL setting hasn't grown into its current state, it's devolved into it. Monsters encroaching into the farmland needed to support the city is exactly the sort of threat the PCs are there to counter. Without the PC's, it's quite probable a lot of the points of light will collapse in the next few years.I think that's the whole point. Because the economy has shrunk to a scale where it can't normally support itself, salvaging high quality materials and tools from ruins is necessary for survival.