It would be really great if someone wrote up an article describing exactly what the "Outbox" and "Inbox" model is for nostr clients, how it is implemented, and the benefits. Then actually keep sharing that article. A long form post would be useful. Link it from popular websites etc. Nostr has a huge search and discovery problem, so we can't rely solely on nostr to convey this either.

This isn't clear in the NIPs, and can only be inferred from assumptions and speculation.