The main issue with Fediverse is the vast majority of people don't know what it is. And I would suspect that most readers of Hacker News only know about Mastodon. The Fediverse needs the same kind of evangelical missionaries that made the free software movement such a big deal.
Who knew what the Internet was when it started spreading into the mainstream? People don't need to know what something is or does to start interacting with it, it either needs a smooth enough onboarding process that people can easily experiment, or it needs some compelling value that they've heard about from others to make the extra effort worth it. Not sure where the Fediverse is on either of these points.