Some Lemmy servers on the threadiverse seem to have a theme (and are not general generic servers).
For example, https://programming.dev/ focuses on (computer) programming and other highly technical topics related to (computer) programming.
I think for a themed server, they would probably want to pick and choose which communities from other Lemmy (or Kbin) servers they syndicate to their home-page or wherever (in addition to their local communities).
I do think syndicating communities from other servers is beneficial — but I don’t think just all or nothing is a good approach.
I think Lemmy should let Lemmy sysops pick and choose which remote communities they syndicate on their home-feed or wherever.
More than a decade ago, this was the canonical pirate video for the English speaking Internet:
Lazy Town | You Are A Pirate Music Video
Enjoy 🙂