I mean a server that can handle clients at scale. Certainly, it's possible to do this sort of thing in a more decentralized fashion, but the games that I'm aware of don't do this.
Plenty of MMO code is single threaded. And almost none of it needs much RAM. They may happen to put it on big servers because it's slightly cheaper to use big servers, but that could easily be configured to use tiny servers.
Handling a thousand people in the same spot can be done on any size of server, and most of the time you're looking at under a hundred.
Handling a thousand people in the same spot can be done on any size of server, and most of the time you're looking at under a hundred.