The signup process is always a sensitive part of a cryptosystem, and open network membership is not always expected (for instance, CBDCs, Ripple…). There is certainly a philosophical argument to be made against closed membership, since it can disadvantage people that struggle for access, and lets the company discriminate in the future once they get a stronghold, which can be especially problematic considering the primary value of human-uniqueness is to restrict voting to an in-group whose bounds historically have been heavily argued even in non-repressive regimes.

But it seems unlikely to become predominant. Some people have prosthetic eyes; I would be hard-pressed to imagine, say, Apple releasing an iPhone that is inaccessible to a population in such a significant way.