This doesn't explain why that #ProprietaryPlatform (#Discord, #Slack, MS Teams, etc.) were initially chosen for that specific group of people. The person who made that decision did it for other reasons.
But it does explain what you asked: Why is this so popular, i.e. why are *so many* people continuing to use it?
#NetworkEffect and #SwitchingCosts. Nothing much to do with the properties of that particular platform.
#ProtocolsNotPlatforms avoids those problems.
#SwitchingCosts: One people are on #Discord or #Slack or whatever, they've got their group meeting there, often primarily and by default.
It's a #ProprietaryPlatform, so they're hostage. Leaving would require abandoning *that group* of people. For many people, they really need or want to stay in that social group.
And that means they must stay on the platform with the proprietary bloated surveillance client.
And, worse, bring new people in and hold *them* hostage too.
