That said, it's got a few features that people have pitched as the solution for HN (tags being one of them).
I ask because a forum project is on the back burner for me and this kind of thing is relevant to my interests.
I also think their invite-only membership policy puts them on a different community-growth curve than an HN, Reddit, Metafilter. I used to scan through the lobste.rs headlines, but i've switched back to a mixture of subreddits, because I can actually contribute more there.
I can see how that might stifle discussion.
Although... temporary guest accounts with joint karma might be an interesting idea.
https://lobste.rs/s/wnqz13/tag_filtering_now_available_to_lo...
https://github.com/jcs/lobsters/commit/249dd85ec3e0d36f6d87d...