Exaple:
40% Horde, 60% Alliance
Server online go down for both sides, and when for horde online is so low, that all active players for this faction on this server, just all go to other, all guilds and server is now empty for this faction and people who want to start game, know that this server faction on this server dead and didnt reg character on it and it keep be empty
Alliance online is go down too, but slower cuz it’s have more active players and new characters regs more often