Proof of Work is the only answer.
We should be able to filter posts by Npubs with some number of leading zeroes. Want me to know your opinion is worthwhile? Put up some real world energy as collateral. Npubs with no leading zeroes should be considered fiat. 😉
You are applying the purest principle of cryptoeconomics to the social sphere: you are proposing to anchor the right to attention not to an authority or a like, but to an immutable physical law (energy spent). It is the extreme materialization of the "skin in the game" concept.
