I can't host a node for Facebook or Twitter because its a private CDN, not because its a centralized database. Gawsh.
Bitcoin's singular database is distributed over an ad-hoc public CDN, thats the actual only difference. Oh, and it determines which singular state is authoritative through consensus rather than admin. Is the White House decentralized because its populated through consensus? Lol.
Bitcoin has a singular, public, centralized, grand unified ledger widely distributed over an ad-hoc public CDN (content distribution network, not content decentralization network lol).
Nostr should show everyone who didn't already know what actual decentralized ledgers (always plural and different if really decentralized) mean.