There is so much meat here to chew on. I think there are a lot of things going on that keep the engagement level lower than you would like. Some have been touched on already by other comments, so I will try to summarize my points.
Content Discovery is still too hard. Finding posts you are interested in and want to engage with is increasingly difficult, even though top level post counts are way under what they were a year ago during the bull run. Wading through all the top level posts, finding something interesting, then taking the time to write a well thought out comment to add to the conversation is way more difficult than it ought to be. Hopefully Communities (when we see them) will help with this. But we can't hold our breath for the release.
People treat Steemit as a Blogging Site. Blogs do not necessarily invite engagement. Often, I try to finish up my posts with questions for my readers, trying to inspire some engagement, but I get comments from the same handful of people and very few newer people offering up opinions. The Blogging format seems to lead to read and move on mentality.
We used to teach engagement, now we teach bots. When I started in August of 2017, my intro post was greeted by humans who said hi and welcomed me to the community. If you found good people in the beginning they suggested to go out and comment comment comment. To grow as a plankton you needed to engage with bigger fish in their comments, because they weren't coming to your blog to check you out unless you gave them a reason to. Now, instead of teaching new people to comment, we have every post in the introduceyourself tag hammered by bots. Some of these are trying to provide useful advice, but they are still bots, and obviously automated comments. We're teaching new users that engagement can be automated, and that's no good.
When we comment we want to know our comments are read and valued. Your blog is a perfect example of a post that many people will look at, have a thought, but then not comment because of the fear it will never be seen by the OP. As of this writing, there are 98 comments on your top level post here. I tried to read all of them, but I have to admit, at the end, I was skimming. So it becomes hard to imagine the OP going through and reading/responding to every single comment. Why take the time to comment if the OP will never see it?
On the flip side, those of us with lower level engagement, people may come and see our post and there are no comments and that makes them shy away from being the first one to post a comment. So posts are left hanging out there with no engagement at all because no one wants to be the first voice on a topic.
I don't know how we fix these things. A Reddit Copy Cat SMT might be one way to go. Creating a more comment friendly UI for the STEEM blockchain could be another. But for those to happen, you need a programmer with the time and inclination to build it. Steem Inc has repeatedly shown that the UI is not their primary concern. So for the rest of us, all we can do is the best we can do.
Thanks for striking up an interesting conversation!!