The issue is relying on relays to propagate your NIP-65 note to ALL other relays. It might not propagate to ALL of them if you’re just trusting it to propagate. Negentropy with interval-based syncing will help though, which were coding in Go.

The blockchain OTOH is the ultimate central repository (that’s ultimately decentralized) that any relay can use to check which relays you’re committed to.

I think Gossip is a great start that doesn’t use on-chain data. Just saying, if we want to take it farther there’s a way to do it without needing to pay on-chain fees everytime you post. The blockchain is valuable if it can be made cheap for users.