I am going to guess that segmentation provides flexibility, and to down stacking prevents from lateral blows, which most sword blows would look like. It would not be great against anything top-down, but most blows would not likely b elike that (top down stabbing comes to my mind, but that would be rarer i guess, much more rare at start or moddle of fight, because at the end, the winner might like to stab to give a finishing blow)