You're right that a Merkle tree is sufficient for censorship resistance when the criteria in your linked comment are met. (I read that comment earlier and enjoy

You're right that a Merkle tree is sufficient for censorship resistance when the criteria in your linked comment are met. (I read that comment earlier and enjoyed it!) So I'm changing my argument: I think key succession is very important and blockchains do it better. When you revoke a PGP key, you have to rebuild your web of trust from scratch, right? The key is your identity, and continuity is hard. With blockchains, a program is your identity. I can trust your new key immediately if the backup process your program encodes has been fulfilled. PGP keys can't be used to build identities that are as permanent and resilient as state-issued identities. Blockchains can.