So, that gets down to the question in this poll: "Should ActivityPub servers send public activities to all known `sharedInbox` endpoints on the network?" Implementers actually have a choice.
There are upsides and downsides to this kind of public propagation. The upside is that public activities are spread around to many more servers. That opens up conversations to more people, makes things more lively and interesting on the Fediverse. It makes the Fediverse feel more like one big place.
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