FWIW, we talked about using things like hashcash to prevent abuse and similar attacks for anonymous remailers back in the early 90s. Talking about it is one thi

FWIW, we talked about using things like hashcash to prevent abuse and similar attacks for anonymous remailers back in the early 90s. Talking about it is one thing, actually making the commitment to do it is something else entirely. Given interest in cryptocurrencies there has also been a lot more effort devoted to considering the cost/feature tradeoffs of various PoW mechanisms (and a broader familiarity with the general concept among the target population), so it is possible that we are seeing a happy side-effect of years of cryptocurrency hype.