A bug has been fixed that gave Chaos Dwarfs increased chances of constructing buildings that were not towers in provincial capitals.
The likelihood has been strengthened for Chaos factions to relinquish settlements that cannot be dark fortresses or are in provinces where dark fortresses can be built.
Thanks to the user Sleepy, whose comment prompted me to review this section and make improvements.

Updated for version 6
The new settlement razing possibilities have been greatly reduced, but the settlement pillaging possibilities have been maintained. Some minor adjustments. I have noticed that Chaos armies now do give away minor settlements to their vassals.

Updated for 5.1
Some adjustments to WOC occupancy decisions