I wonder whether what Anubis is doing might be blocking agents that do not run JS or that have a timeout (or humans who give up as I just did)

I suspect that's most of the value, and that the deterrent is about software construction and not about the proof-of-work, which I've been saying for the last year is a productive direction for Anubis to head towards. Instead, it's just sort of tormenting normal people, as a kind of performance of anger about AI.

Which: I get! If it's your site, perform all the anger you want.