Kbin is essentially the same as Lemmy.
I also would say I don't think the graphic is correct about the way "all" works. I'm pretty sure "all" is content from all local and remote communities any local users have subscribed to (which is shaped both by local user activity by the federation graph that local and remote server admins control). Communities on servers that admins have defederated from will not appear in "all".
So... individual local users and admins shape the "all" feed. I don't think there's any way to get a global feed of all Lemmy activity.
The Infinity dev says he's working on a subscription version that is not ready yet.
There was another app developer doing that also (Boost? Not sure) and the developer said Reddit gave him and his users some grace period to get the new version out.