I'm on a sports team messageboard that still runs on a mid-00s phpBB backend. There are no bots because there is nothing to propagandize about on such a small, topically focused community.
The age of small self-hosted forums is unfortunately behind us, and I don't see them reviving any time soon.
The underlying software is not really important, it's what you can do with it.
I wish more people would try Discourse, which is threaded like a real messageboard without all the automation bells and whistles.
If HN was a sub reddit I would never visit it.
Also younger people find forums archaic and weird, to the extent that most people my age (early 20's) that I've talked to about this prefer imageboards over forums. As much as I'd love for forums to make a comeback, younger people are the ones who determine the next shape culture will take and there is very little chance small forums will grow. It's such a shame too, it's so difficult to find good Discord servers and so much technical knowledge is unindexable and will most likely be lost forever once Discord stops burning money for growth.