I said, “it works”. In terms of the user who wants to be spam free.
And it is fair.
I do always think user first and not mass first.
Of course it is not “popular”. Because email is not popular anymore.
I mean some friends use hashcash.
Personally I doubt that paying with energy is better than with money!
Cause of climate crisis.
Feel also free to propose better solutions to Chris for the paper …
It might depend what you build and who your users are of course.