Blockchains aren't decentralized. The Bitcoin blockchain is a grand unified centralized ledger of every fucking transaction across the entire currency, with 1 authoritative version that is synced up across multiple host nodes. That's distributed, like Facebook; not decentralized, like Nostr.

Nostr is akshully decentralized. No ledger (db) contains all the data. Each node (relay) hosts a different subset of data that doesn't require any other nodes or all the data for the system to work 'properly'.

Blockchain enthusiasts absolutely adore massively centralized, distributed systems.