Technically speaking, Friendica, Hubzilla, (streams) and Forte ought to be parts of the Threadiverse, too. They've always had enclosed threaded conversations and even discussion groups built in. Except for Friendica, they support FEP-171b "Conversation Containers".

But look at how few people on Lemmy have even only heard of Mastodon. Friendica is much more unknown there. Those who know Hubzilla are a subset of those who know Friendica. And (streams) and Forte are next to completely unknown beyond Hubzilla's actual users.

[–] OpenStars@discuss.online 3 points 22 hours ago

Tbf if you are interested in topics rather than people, then Mastodon is simply inferior to the Threadiverse - as you gave the best description I've ever seen on that point.

Friendica is inferior as well, but more on the technical side. It is struggling and instances shutting down due to lack of stability and efficiency, with costs rising far too high along with number of users. They've put out calls for programming aid to help fix those issues. As a non-user, I thought their main focus was on people rather than topics of conversation though?

The Threadiverse has quite the reputation for having such solid products - whether written in Rust with custom front-end or in Python with flask front-end (and Postgresql back-end), or Mbin is in PHP, and nodeBB uses Node.js.