I don't think the issue is that it is too easy to change identities. Vouching or slow starts both lead to much more closed systems. You could say that is a solu

I don't think the issue is that it is too easy to change identities. Vouching or slow starts both lead to much more closed systems. You could say that is a solution for the posed problem. "A more closed system". But to me, a more closed system is less valuable. Certainly it lacks the network effects that seem to be needed these days to make it financially.