Thanks.
Making it expensive to create identities directly undermines the goal of having mining not controlled by particular parties.
I do not understand this. The two issues appear disconnected to me: one is how to create "expensively" identities for miners. The other question is how to preserve decentralization.
Hence, a very interesting question is the following: "Is it possible to "expensively" create new identities in a P2P way" ?"
Moreover, any such scheme has some optimal strategy where the cost of identities vs exclusion are counter balanced, and in general complicated strategy favors larger parties (who can afford to figure out and implement the strategy).
I also do not understand this. I gave above one possible example on how to create identities expensively" that would not favor larger parties. Other centralized examples could be: prrof that you run a marathon, that you achieved a certain ELO at chess, that you have a piece of art exposed in a museum etc.
...it wouldn't work because parties could permit others to use their identity. (E.g. to mine at this pool you must obtain an identity and allow the pool to use it).
As explained above, this would need to be combined with some exponential backoff mechanism, in which case it does not matter whether it is permitted to share identities.
In any case, it's hard to comment with more than these sorts of arm-waving generalities against a proposal which is itself an arm-waving generality.
Please take the time to concretely work out how to intend to issue and manage these identities, and what effect(s) you have them to have before asking other people to spend time considering your idea. Otherwise any reviewers time investment is unboudned as you can continually reveal previously undisclosed features which patch over their concerns one by one.
My apologies if you feel that I am wasting your time and/or others. I was under the impression that it could be a useful discussion to have.