Decentralization doesent mean:
* federation
* mesh networking
* peer to peer
* onion routing
Those are possible solutions, but decentralization doesent require the use of these.
Now, thanks to nostr:npub180cvv07tjdrrgpa0j7j7tmnyl2yr6yr7l8j4s3evf6u64th6gkwsyjh6w6 we have am entire new architecture for decentralization: symmetric store-and-forward relays or "rally points"
Evidence this is a new model is seen with the recent emergence of SimpleX, which operates on the same model. The only difference is the nature of the relay's storage, one is ephemeral and encrypted, the other is indefinate and unencrypted.