>>281432435
Expedience. Discord is something that a lot, not all but a lot, of people already use, it's free and doesn't require hosting, and it's basically 1 click to join so the barrier for entry is low.

I wouldn't be completely opposed to using something like Riot (although I dislike the idea of having another client, and I think it's obscurity might discourage use), but I think most people's objection to it isn't the service but the existence of identity-based alternative communications.