Once upon a time, there was an acronym we used for certain sorts of virtual worlds. We called them PSW’s, for “persistent state world.”
Most virtual worlds today don’t actually have persistent state. Oh, your characters do, but not the world. In fact, the ability to affect the world has fallen dramatically since the days of Meridian 59 and Ultima Online. M59 featured shifting political balance, and UO had full world state persistence. If someone killed Bob the baker, he was gone. If you dropped something on the ground, it stayed there until it rusted away (or more likely, someone came along and grabbed it — and that someone was just as likely to be a monster as it was a player).
It took half an hour to 45 minutes to save all of the world state in UO, by the way. Which meant rollbacks to your character if the server crashed. 🙂