[0] https://blogs.cornell.edu/info2040/2015/10/14/the-evaporativ...
The one problem specifically with reddit and other 'frontpage' type communities is that they don't surface where the actual conversation is in the way vbulletin or other forum software does. With the old reddit code, however, you could go to https://old.reddit.com/r/subreddit-name/comments and see a comment view of the entire subreddit. This would bring the current conversation to the top regardless where it is in the standard view. Really improves the experience for smaller subreddits that don't have much traffic otherwise.
Unfortunately they seem to have removed the feature in the new code. You can still use it in old per above however.
Depending on the newsreader, you could essentially get the same thing by having the thread with the most recent comment move to the to of the thread list. Then, expanding the thread would show new comments in bold font to distinguish then from ones you've already read or previously downloaded.
Being able to see new posts is something that's lacking in reddit and HN (though reddit does provide this feature on subs you moderate or have reddit gold).
The continuous fountain of content model at reddit/hn/digg/etc is good for retinal adhesion but not so good for exchange of ideas.
Experiencing the transition has made me value small communities much much more.