Does anyone still want to argue for skiing square to the skis????

Marcel Hirscher in GS, like all the top racers he uses Counter Acting with his hips and torso, to stabilize the upper body and keep from creating any rotation. Rotation squares up the torso and loses the back of the ski. Rotation also makes a skier use upper body movements to start the next turn, this is much slower and throws you out of balance.
For recreational skiers, add more counteracting to your skiing and hold a better edge. Few skiers can ski with a square hip, it's a much weaker "position". Counter acting requires a movement to achieve it. Square is a position. PMTS skiing relies on teaching movements not positions.