Did you ever play Asheron's Call? Their servers shut down around 2017 or so, and before that happened, some people dedicated to preserving it handed out programs to players to just run while they played and it tracked NPCs, mob spawn locations, quests etc. Once the servers shut down, they painstakingly recreated the game as it was on the final day. Since then, people have setup their own custom servers with additional custom content (unlimited levels, raising stats, crazy tough mobs, new weapon and armor tiers etc). Even though Warner Bros has not run anything regarding this game for the last ~10 years, all of the server hosts are very diligent about not collecting any fees (even to just cover servers costs) and hand out lifetime bans if anyone tries to sell their gear or account for IRL money. Kike lawyers will be quick to sue anyone making money off of the IP, so if those WOW guys had taken such an approach with their servers, they probably would not have been bothered.
Never played that but I am on the side of "if you shut it down it's fair game". They could have kept it running, created content but rather they decided to kill it with no way to even play the original on their own.