This seems to trying to pin down the "problem of identity" (how to ensure people maintain a stable identity over a digital realm) I think it's important to be

This seems to trying to pin down the "problem of identity" (how to ensure people maintain a stable identity over a digital realm) I think it's important to be clear about why this is important, depending on the use case (votes, currency, etc) there may be a different reasons why it's important that one identity follows one person. In the case of currency, the reason behind needing stable identity has to do with double spending. But I have a toy scenario that I like to play around with, consider a cryptocurrency such that anybody can emit tokens (credits) however they deem appropriate, in this case the necessity of a stable identity is clear, the person needs to be able to answer for their emited tokens. If people can just shed the token-emitting-identity, then they cannot be held accountable (forced to answer) for their emitted tokens and the entire construction is useless. However, for the case of votes and other group-concensus schemes, the scenarios are sufficiently different that I'm not sure if it'e even worthwhile to try to come up with ONE answer to the identity "problem"