> Anubis wants "slow for bots but fast for humans"

That's not true. The goal is to raise the cost for bulk scrapers to the extent possible while minimizing any inconvenience to regular users. It's not about being slow for bots but rather reducing the asymmetry of the problem (from the perspective of the server) by imposing a (minor) cost on anyone requesting a page.

One possible way to do this: rather than simply burning hashes for nothing, Anubis can burn hashes to mine crypto. This way, the bots pay for the infrastructure they consume, at least in part.

Combine with heuristics like in the article, so you can crank up the difficulty only for likely bot traffic, and you've got a bot supported site.

> [...] which is not possible if somebody has a farm of devices that costs them basically zero.

Opportunity costs are real.