It's annoying that such a large portion of the open source community still use Discord. Even if we disregard the recent events with ID leaks and such, there's so much wrong with using a proprietary platform like Discord to chat.
I'm of the mind that if people want to use one thing over another, they're of course free to do so. At the same time though, Discord should really be the antithesis of many projects' goals in terms of privacy and openness.
The only explanation I can think of is that alternatives truly must be horrifyingly terrible to use, which would certainly be an impressive feat. I assume the alternatives are like what ReactOS is to Windows--a very ambitious goal, but also not in any way a viable option if you actually want to use your computer.