I think Discord, especially when it was new, had amazing UX and UI. Nowadays it definitely became bloated and new features don't integrate that well into the existing UI, but it is still on a perfectly useable level, currently.
Discord's UX is a testament to the fact that people will learn complex systems if they believe all parts of the system are valuable. This is the same truth as, for example, spreadsheet software.
The only thing "bad UX" means anymore is that you have parts of your app that people don't find valuable, and you're showing it to them anyway.
