BTZS says nothing about art or creativity, it tells you about craft and process and having your process produce the results that you desire. Art without craft is laziness/incompetence, craft without art is pointless. You need both and BTZS doesn't pretend to address both. You don't need sensitometry to do art, but there are some scenes that are easier to capture more reliably if you have the sensitometry, in other words I think the point of BTZS and the like is to learn enough that your lack of craft doesn't hold back your art.