Are you filtering or looking at the firehose?
I currently see about a half dozen or so topics on the first page that would be considered (or close to the threshold) of "hot topics" in the old forums. A few with a couple of hundred replies. That's about what I recall being typical volume before (give or take).
If a member is using a filter (or stacking filters) then they are seeing only the threads that meet their tag filter.
Either I am not being clear or I am not understanding you.
Are you browsing the forum with a filter on #theflood? If so, you will only be seeing/getting a small fraction of the threads that are being posted (you will only see topics that someone has manually added that tag to, and even by your own admission, it's easy to forget to tag).
If that is what you are doing, you may want to try watching/browsing the "all topics" filter (which is no filter) and see what everyone is posting (and then hide/mute content or members who don't fit your expectation or definition of "good").
Because if you are using a specific tag to browse, then you are only going to see topics that have that tag attached.