When I visit kbin.social, I see new posts regularly. On other servers posts stay on the frontpage for multiple days. This is also true if I switch their sorting to “hot”. So that is probably not the difference.
What is kbin.social doing differently?
That’s the magic of ActivityPub! It’s the protocol that most of the fediverse is built on, and it lets users from completely different fediverse platforms share posts with each other. It’s the special sauce that lets Mastodon, Lemmy, and kbin (and more!) work together