That is not a productive way of thinking about it, because it will lead you to the conclusion that all you need is a smarter proof of work algorithm. One that's GPU-resistant, ASIC-resistant, and native code resistant. That's not the case.

Proof of work can't function as a counter-abuse challenge even if you assume that the attackers have no advantage over the legitimate users (e.g. both are running exactly the same JS implementation of the challenge). The economics just can't work. The core problem is that the attackers pay in CPU time, which is fungible and incredibly cheap, while the real users pay in user-observable latency which is hellishly expensive.