The server was packed even (perhaps especially) in its final moments, with the kind of crowds the official version never sees anymore:
https://www.youtube.com/watch?v=Y86hk_93d4c
(1)By calling it a realm instead of a server I suppose I out myself as a former WoW GM.
(2) Fairly typical player density early in Vanilla (in an atypical and hillarious situation): https://www.youtube.com/watch?v=CZ_WdYvwrDA
Their second server was also reaching ~5,000 players at the time they were shut down.