Previously, if a post was commented, it would bump to the top of the list
Now, it seems the design is comments never bump posts - although perhaps it's just "broken" because of delay?
This means long threads never develop. Once a post is a day or two old, it slips off the front page, and no one notices it.
And, perhaps surprisingly, the change to put recent-comments-first was a design mistake. It also works against long threads developing, because people don't even see the discussion.
For your long-term contributors, people who do more than ask "where should I eat near union square", the long threads are what makes the site worthwhile.
There are a number of reasons the SF board is down to only 3-4 posts per day and fewer and fewer comments. The loyal long term posters have weathered a lot of site downgrades, because the fundamental fun of the community is here.
But now, with the site just being "recommend this", I'm certainly posting less, and this will be my only post on this topic.
Ironically, I can't see easily if there has been a long involved discussion on this topic in the last month, the kind that would keep getting bumped to the front and probably still be there.