And in a world where the formal duel is a constant presence and risk, no one planning to wear a katana would learn the one without the other.
Well, but kenjutsu is not only about the katana... A Moto Bushi might have all the ranks in kenjutsu so that he can wield his scimitar like a pro, but zero iaijutsu because his katana is on the stand in his tent 24/7.