Your theoretical counterargument falls apart by the reality of just putting up anubis and comparing the before and after. I don't understand why this argument shows up in every thread about anubis. There are plenty of people and orgs who have empirical before and after results. We don't need theoretical arguments when there exists actual data.

The exact claim I was replying to "It does that by increasing the cost of scraping, not by preventing it entirely." In that context, quantifying the cost isn't theoretical nitpicking!

Anubis works to the extent it does because in counter-abuse security by obscurity tends to be the best security of them all. Right now Anubis isn't popular enough for many scrapers to try working around, so they don't. But they will pour resources into working around Turnstile and Recapcha. In this regime, the exact challenge is irrelevant. Anubis would be just as effective if the challenge was running a javascript function to add two numbers instead of a proof of work.

Proof of work is just a uniquely dismal basis for a counter-abuse challenge.

It's not because of the PoW though, it's just because the scraper doesn't run JavaScript. The alternative package called go-away does these tests without the PoW.

Captchas worked for a few years too. Then computers got better at solving them than humans, and we're still dealing with the fucking useless things decades later.