One thing I miss about HN type forums is the "here is what you haven't read yet". When an article has 100 comments and I've already read 75 it is rarely worth my time wading through to see the new ones. Even though I know from experience that writing a good insightful comment takes a lot of time. Most of what I'm missing will not be very insightful, but I'm sure I'm missing some of the most insightful comments. It also discourages me (and I assume others) from writing a long insightful response at times because I most of the people who would be interested will see it.

lwn.net does that well, highlighting unread comments as a perk for higher-tier subscribers. I wish it was a more-widespread practice.

It should be trivial to write an reader program for hn that does that.

These days you might even vibecode it in one prompt, although coding it manually is not super hard either.

There was also a locality to BBSs (less so the distributed relay systems like Fidonet) because of the cost of non-local telephone calls. I was a subscriber to a BBS is a relatively nearby city (though telephone costs were still high--used offline readers). A number of us would get together in-real-life semi-regularly.