Because the idea of the build and concept is to switch swords instead and gain a damage increase for all attacks. We use Winz Az's build as a concept build because he's probably the most famous for this style of play. Maxing all the stances however does become less of a requirement later because the bonus damage will all be allocated to Force instead of being distributed around all the moves. This idea is what I've also adopted as well, however I use other sets in the meantime before the WM rework that took place in Korea February this year. Switching becomes one of the better strategies once that patch comes out. For now I would say Max should probably go for Afterimage first and Deadly second, as the patch won't come out for long even after you get the second set. I've left Drive and Thrust in their 30's and kept my cube moves higher than Max, but Max can do Max.