Earlier quoted context omitted.
It's interesting to see how much of a behemoth Discord has become. Seems like there's a Discord for everything - from open source projects to hobbies and games to individual groups of friends/family. It's occupying the segment that subreddits historically have. However, it's perhaps-intentionally search-opaque. You can't Google to find a message/link/download that's gated by Discord. And it also gives a sense of comm…
Discord is IRC, just with modern features. I wonder if there are any old school protocols out there to create a huge business around by just centralizing them and offering features people have been asking for decades. Probably not.
React was the first open-source community I knew of that outgrew/got kicked off of Slack and moved to Discord. Now, it seems Slack is only used by companies, and occasionally by smaller groups (apartment buildings, school parents, etc) where someone in the group knows Slack from work and doesn't know it's hostile to non-businesses.
Discord was the opposite. I was working on an open source initiative at Google at the time, and the Discord folks openly welcomed us. They even gave us someone's contact info, in case we had needs they weren't addressing. This was when it was still targeted just for gaming, but they were very welcoming of OSS projects using it too!
As I write this, I realize that Discord is what "Google Apps for your Domain" was and Slack is the "Google Workspace" it became.