This is one of the very few non-money-laundering use cases for crypto.
I would support a “5 cents per unsolicited email” email system, in a similar way. If you make it a mildly enjoyable $5/hour task to read the first sentence or two of your spam folder, the overall internet would be better.
This achieves the advantages of quick blocking while deterring bad behavior, and provides cost-effective recourse for publishers that get blocked, since the bond would cover the legal fees of challenging the block (lawyers can take those cases on contingency and get paid on recovery of the bond).