From what I gather the idea for Anubis isn't to _stop_ bots, it's to make them slow down enough to not bring down servers. Like they said in the presentation,

From what I gather the idea for Anubis isn't to _stop_ bots, it's to make them slow down enough to not bring down servers. Like they said in the presentation, git(lab/tea) instances have insane amounts of links on every page and the AI crawlers just blindly click everything in nanoseconds, causing massive loads for servers where normally there might be a maybe a few thousand git pulls/pushes a day and a few hundred people clicking on the links at a human pace. Plus the bots are made to be cheap, fast and uncaring. They'll happily re-fetch 10 year old repositories with zero changes multiple times a week, just to see if they might've changed. Even a if the bad proof of work requires the bots to slow down their click rate, it's enough. If they somehow manage to bypass it completely, then that's a problem.