When/how did guilds, which were (to simplify it) essentially the first instance of Trade Unions, become the main term to describe groups of players in MMO games?

by Gnivil
Iphikrates

r/AskHistorians normally does not allow questions on very recent history - see our 20-year rule. However, we've decided to let this question stand, since multiplayer online games have technically existed at least since the early 1990s.

When answering this question, please bear in mind that only discussion of these early MMOs is allowed on our sub. Answers related to games from the current millennium will be removed.

Thank you!