For example, if I (on kbin.run - which is Mbin, but for the purposes of this let's just assume it's Kbin) go to a random magazine on kbin.social, I will often see a prompt that the magazine may be incomplete and that I should visit the original instance for all the content.

Why doesn't the request to that magazine automatically trigger a "pull" from that instance for that magazine, or at least cause it to check if the number of threads is the same (and conditionally pull on that)?

I get that it would be a lot heavier of a load on the servers, but in combination with good caching techniques (maybe setting a time of 1 day or something until the next pull occurs, idk) I feel like that could be mitigated.

Is this maybe an implementation detail of ActivityPub?

Thank you!