Paying fractions of a penny to view websites has minimal impact on average users but is punishing to spammers.
That is, do the proof-of-work before visiting the website, then present the currency token that proves the work has been done. The blockchain is there to prevent double spending of the currency token.
I do feel like this is a kind of "those who don't understand it are doomed to re-invent it" type of technologies.
You don’t need to worry about double spending or any of the privacy issues that come with a blockchain when the work is done real time. I know exactly how much work is being done on the server per request with this solution - one hash. There is no need to crawl through a block chain, or submit a transaction, or wait for an external system to catch up.
I want a solution to these crawling bots, not a distributed database. So why would I reach for a distributed database when this simple proof of work system works better, is more understandable, and doesn’t have external dependencies?
I'll mention that, in an extreme case, one could provide a proof-of-work challenge that's directly tied to some cryptocurrency mining effort, so that the work/energy expenditure is captured by the one providing the challenge. This has the effect of the challenger giving money to the one providing the challenge, just in a real-time proof-of-work way. Since money is effectively being exchanged anyway, this punishes systems that don't allow up-front payments to do away with the page load delay.
And no, "anonymous mixer" services don't work either. They're yet another layer of useless profiteering middlemen, which the web already has more than enough of.
I wouldn't trust anything to be safe from the dragnet surveillance apparatus of FVEY.
The problem is, if you want some "proof of money"/"proof of stake", site operators set that up on their own which is a ton of work and people will not want to set up payments for their favourite porn site AND the government can trace back people from payments to site visits, or site operators contract a major vendor (similar to Stripe, Paypal, ...) who handles it and can then trivially be subpoena-ed for records.
Although true in an ideal financial sense, it's demonstrably false because having a pay wall of any kind will severely limit usage.
My view is that when the payment threshold is so low, the issue is inconvenience or user friction, not the amount of money involved. I suspect people would be fine with small payments if the user experience was better. For example, Amazon, Netflix, iTunes or Spotify.