They never really left. They've just changed hands and homes a few times. And actually, that address really just links with the current site of http://worldofmodcraft.com/forum/ Have a look around the site - there are tons of UIs for you to look at that were created in the past year.
Seriously, to each their own. If people like to use discord stuff and are happy it's available, good for them. Noone makes you use it anyway.
Too bad drama may eventually lock this thread, but OP certainly didn't deserve that, except that I don't know why this forum specifically needed to be alerted to DUF, but naively there should be no harm...
And yes discord stuff has been used all this time, quite a few compilations and UI setups around that used kept-alive discord. I didn't quite follow it all that much but maybe the fact that it's patched up for 3.0.3 is news.
If that was your opinion why not report the post and let mods handle it instead of the trolling/hate-mongering? I for one am reporting this thread now, so this will end one way or the other, you are hell-bent for the drama anyway.