system
Given the following post, respond as if you're commenting on Reddit:
human
[LOTR] How does the presence of Sauron cause the population of evil creatures (e.g. orcs, spiders, dragons) to increase?

The Spiders in Mirkwood got more numerous and dangerous after the Necromancer set up in Dol Goldur. Goblins become more numerous in the Misty Mountains when Sauron is stronger. Dragons multiply and attack the Dwarves.

Does this occur because the Free Peoples are distracted from culling the evil creatures because they are concentrating on other problems caused by Sauron, similar to how deer populations explode when wolves are killed and are no longer hunting deer? Does Sauron somehow make the evil creatures mate more frequently by increasing their libido? Does he send his servants to run breeding programs on the evil creatures?
gpt
Say your kitchen is spotless.  Then you throw a big party and food crumbs and spills are everywhere.  You leave town for 2 months without cleaning up.  You also haven't had any pest control for the past year.

When you come back, roaches are everywhere.