Caporegime
Then they just need to quit or block the people that annoy them.
Yes, but (a) many of them aren't mature enough or self controlled enough to do that, and (b) even if they do block them, they'll still know that they're there, and the very thought that these people are back on Twitter is intolerable to them.
In any case, it's not just about wanting to reduce content that annoys them, it's also about wanting their opponents to be perpetually punished.
Hopefully they can improve the platform - but it seems to be in a death spiral.
People have been predicting the death of Twitter for years, it never happens. Like Facebook, Twitter is now too big to fail.