Just federated identity, like OpenID. It doesn't necessitate distributed systems with communicating backends, like Mastodon or Usenet, just that it allows the u

Just federated identity, like OpenID. It doesn't necessitate distributed systems with communicating backends, like Mastodon or Usenet, just that it allows the user to bring their own IdP and therefore to have "sovereignty" to verify their own identity across platforms. The alternate route is to have users cryptographically certify their registrations post-hoc, e.g. Keybase