popa,
Poskim, especially Ashkenazic ones, will argue on *halachah* with rishonim, even when they don’t have a competing rishon to back them up. Kal v’chomer on a matter of empirical fact. We don’t follow Rambam’s medical advice when it disagrees with modern science. We don’t follow Ibn Ezra’s geography when it is clearly at odds with the actual geography of Eretz Yisrael. The rishonim were great, but they didn’t have access to the facts we have today. They were experts in Torah, not science or geography.