See also https://slrpnk.net/comment/10312933
What you're suggesting can't work
I sympathize with some of it, but you're going too far
Content addressable posts like what Bluesky's atproto does and cryptographic identity allows for portable posts and identities, and it even allows forkable communities as you can import and move entire conversations, and even mirror conversations that one team of mods may not like into another community (I made my first blog post about content addressable forums literally a whole decade ago)
And when posting to any /c/books the default visibility should be the same assuming a neutral reputation server and a neutral reputation user.
Literally impossible according to the CAP theorem (database terminology) in a decentralized network where not all servers federate with all (often because they just never have interacted and thus don't know of each other)
You have to push the communities to participate in multiple parallel communities, that's much more reliable. Together with a credible threat that the community can depose bad mod teams by forking, you have a much better chance of preventing bad mod behavior
They're not for long term storage, they're for transient storage like photography, in particular stuff like surveillance cameras