The use of "server" to mean "instance" is very old. For efficiency's sake, multiple separate instances of old FPS games can be run in a single process, but I do

The use of "server" to mean "instance" is very old. For efficiency's sake, multiple separate instances of old FPS games can be run in a single process, but I doubt you would object to the vernacular of "Quake server" as short-hand for "server-side Quake game instance". Also, Discord internally calls them guilds.