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?
I think the “dynamic updates” behaviour is tied to Lemmy’s use of websockets instead of http. Kbin uses http. The Lemmy devs have stated they’re going to move off of websockets in the future as they present scaling issues with the way the software is written.
The websocket protocol allows bi-directional push communication regardless of the previous request which means that new posts are constantly triggering server side updates which then appear like a page “refresh” on clients.
Arguably, while websockets have very cool realtime features compared to http, for a Reddit-like content aggregate their use can quickly overwhelm usability without significant retooling.