The key thing about Jack's post re: protocols is that it's not about the protocol. In some ways, it never was.
The hard part is identity, and always was. Twitter's power is in the Users table, and the fact that none of us could ever escape it. It's the reason verification was always such a big deal, and why decentralized moderation is so difficult.
With decentralized but *also* usable identity, we can all use many protocols.
SMTP got it wrong, because the identity was tied to the protocol.
@blaine with ATProto? https://atproto.com/guides/identity