You could still come up with a scorecard for lossy compression, for example area under the rate distortion curve. It would be very hard to calculate.
Even then, given half of any sentence in the book, I don’t rate my chances of reproducing the next half. That’s more a question of knowing the author’s style than knowing calculus itself.
Does arithmetic coding capture all of that?
Now, who will get closer to the algorithm with that added arithmetic coding? You, knowing the proofs, or a random guy that doesn’t even speak the language? Does it then measure intelligence all else being equals!
Arithmetic coding is optimal in turning probabilistic data into lossless data. There's provably no way to do it more efficiently than arithmetic coding. The data it needs for corrections is smaller the better the predictions are.
So given this why even dwell on ways that add any form of subjectivity. Arithmetic coding is there. It's a simple algorithm.