Those are all very good questions, and exactly the sort of things that would be discussed at the ForumWG.

Backfill is just one of the things (the main thing, currently) we touch on, but one of the more important ones, because the potential to ensure you have the entire conversation is important from a data completeness standpoint.

The thing to remember is that there's no one "owner" of a conversation. Right now it's a pretty loose association... individual posts and notes can declare that they are part of a context, even if that isn't the case. This beats the current system where there is no association at all.

The difference here is that as a consumer of backfill, I can actually go to the context and verify this. We can extend this later on with context ownership, and defer responsibilities like moderation, interaction policies, forking/merging, etc.

The long view of this is we intend to increasingly solidify the association between context and object over time.