I would argue that "modern UX expectations" is a large part of the problem with Discourse. Infinite scrolling is one prominent example. Wasteful whitespace is another.
Personally, I love that Discourse allows j/k for keyboard navigation. I get the hate over infinite scrolling. I feel mixed over the two approaches.
https://forum.vbulletin.com/forum/vbulletin-5-connect/vbulle...