I'd say this problem is best solved not by having no cryptographic identities, but by using disposable identities.
If you bound an identity cryptographically to your real name, that's permanent -- no getting around it. We all make mistakes. However, one of the benefits of Urbit is that you can build a reputation around a pseudonym that isn't linked to your real-life identity.
There's a place for the 4chans of the world, with totally disposable one-time identities. You can do this with Urbit as well -- use a 128-bit self-signing identity (comet). But most people tend to want a little more stability and permanence.
If you bound an identity cryptographically to your real name, that's permanent -- no getting around it. We all make mistakes. However, one of the benefits of Urbit is that you can build a reputation around a pseudonym that isn't linked to your real-life identity.
There's a place for the 4chans of the world, with totally disposable one-time identities. You can do this with Urbit as well -- use a 128-bit self-signing identity (comet). But most people tend to want a little more stability and permanence.