The idea that we can understand rishonim by studying the culture that they lived in means that their Torah is not completely Torah, but rather the product of outside influences. Academics who are wholly influenced by everything but torah enjoy validating their interest in the outside world by claiming that chazal, rishonim and achronim were too. They will trample on halacha by saying that things like tav lemaysav were cultural sentiments or even misogyny had they been said today. Are we to take as authoritative, mere reflections of non Jewish societies? Also, how is this approach “evidence based” when it’s simple conjecture and juxtaposition? Let’s say the prevailing philosophy of the hometowns of the rambam and raavad was kach vekach; is that definitive evidence? Can there not be coincidences?
And yes, there is a nafka mina even in this case. As I said, how can a halachik opinion have weight and authority if it’s not a halachik opinion based on the 48 kinyanei Torah, many of which include the removal of bias?