Context: Middle Ages music recreation teds to be a bit more interpretative compared to Classical pieces. There is also a lot of surviving source material for classical music.
Actually, it turns out more and more that classical music can be interpreted in many ways, and composers at the time were constantly improvising from a written piece with new ideas on the fly. Contemporary musicians created some kind of a cult to classical music and tried to enforce rigorous exact playing when in reality that was not the composer's intentions at all