It's good for keeping communication in one place - I mainly use it to host ttrpg games, so my server has all the lore stuff in one channel, general chat in another, character ideas and discussion in a forum-style channel where each character can have their own thread, and a voice channel for when we're actually playing. Each campaign gets its own category, so players can also go back and check stuff out from old campaigns. I'd like to switch to an open alternative, but the few services that offer similar functionality are self hosted or still quite early in development so aren't reliable enough for my needs.