It does work, at least in my experience. The challenge may be cheap for your n-of-1 but keep in mind the scraper bots are crawling number of domains with very high concurrency.
And without control of their source IP addresses. They use a "rotating proxy" meta-proxy which sends each request through a different proxy, which invalidates the Anubis response and triggers a new challenge.
And without control of their source IP addresses. They use a "rotating proxy" meta-proxy which sends each request through a different proxy, which invalidates the Anubis response and triggers a new challenge.