Yes.
Underground monsters, especially Vanguard Controllers, have gone from the inconvenience they were in Cove to being event destroying.
Each time you try to hit a Controller, it spawns more helpers. And since you can't ever kill the Controller, as it's inaccessible, you can't ever "finish."
The cities are lost, not because that was the fictional intent, or because we as players weren't up to the task, but due to a bug.
-Galen's player