What baffles me is that Discord is basically mIRC with some extra features but the culture just isn't the same.
It's not the tools it's the people
As you said, this produces a culture where there are steady pools of people both seeking out the content, and waiting to consume it. The flip side of this is that everyone also knows the game, and manages their online presence so they don't end up on the trending tab of twitter.
On our neighborhood forum, someone could say their lawn mower blade broke, and some jerkoff will start yammering and democrats and bail reform.
Pseudo Anonymity is sort of a key feature of IRC that I think acts like a strong filter for people
People who are jerks will use anonymity to be jerks whereas when they are forced to tie an account to their identity they might pretend to be not jerks
People who are kind when anonymous are likely just good people at their core