So, in your example, each request needs 0.1 core-seconds of PoW. Is that right? Or, since you're saying 10000 hashes across the entire machine and 1000 needed, then on a typical 96-core server you need 9.6 core-seconds of PoW? The former means you pay about $0.0000005 per request at standard cloud rates; the latter means you pay about $0.00005 per request _and_ your site is totally unusable by legitimate clients. Both are _easily_ worth it for someone backed by VC billions and hungry for data. The network and storage fees are likely to be more significant than that already, not to mention actually training a model; they don't balk at downloading terabytes of crap already.
Note that none of this assumes any sort of acceleration from parallelization (be it through GPUs or reusing work across servers) or precomputation relative to what a normal client does. Compute is just really cheap in dollars compared to the cost of having a user wait, and these companies _also_ have a lot of appetite for spending dollars compared to that of a normal user. As others have pointed out, the only reason why Anubis works (sort-of; not for everyone) right now is that it is uncommon enough, essentially “proof that you bothered to have your crawler run JavaScript at all”. It's a confusion measure.
You raise some good points here, but PoW is meant to be one tool in the toolbox, not the only line of defense. You can still maintain blocklists of known scrapers (or better yet, have your PoW system be aware of them and silently adjust the difficulty to an impossible level, such that the scraper gets stuck trying to solve your PoW challenge until it hits a timeout configured by the scraper, if they were wise enough to configure one). It's also courteous to not only build and maintain your own blocklists, but to share them with e.g. vtotal and spamhaus, to help protect others.
Similarly, you have tarpits, which generate infinite mazes of garbage data, or even deliberately poisoning training data (should the scrapers be training LLMs) though this don't entirely eliminate the deleterious effects of scraping on the host's web server (more info: https://arstechnica.com/tech-policy/2025/01/ai-haters-build-...).
If the premise was evaluating whether or not PoW would be a magic silver bullet that stops scrapers all by itself, then you are correct, it does not stop all scrapers. Scraping and anti-scraping is fundamentally a constantly evolving cat and mouse game that demands adaptability and punishes complacency from all participants trying not to lose.
Note that none of this assumes any sort of acceleration from parallelization (be it through GPUs or reusing work across servers) or precomputation relative to what a normal client does. Compute is just really cheap in dollars compared to the cost of having a user wait, and these companies _also_ have a lot of appetite for spending dollars compared to that of a normal user. As others have pointed out, the only reason why Anubis works (sort-of; not for everyone) right now is that it is uncommon enough, essentially “proof that you bothered to have your crawler run JavaScript at all”. It's a confusion measure.
Proof of work does not work.