BTS, Gilles is offering us some good advice and you being so quick to label his advice as heresy and "wrong" suggests to me you are not willing to think outside your conventions but does not represent any heresy on his part. He didn't get where he is by being so wrong and neither did all the demo teamers I have worked with who I would say agree with him more than disagree. Not that I am speaking for them, I'm just sharing opinions they have clearly expressed on this very subject. Perhaps like in Weems' diamond ideas leaving the lion's share of balancing effort to the subconscious and maintaining a strong focus on "in the boot" movements works for you but even LF's dot idea shifts the mental focus higher up the body. And you openly state you like that idea! So it confuses me why Gilles' video is so out of line with your theories.
For me the bottom line here is hip dumps are the direct result of a joint bias that sometimes can be traced to the relatively immobile ankles and feet. Yes we can flex the boot but compared to those joints moving in free space that RoM is minimal. So the joints above the ankle must take on more of the flexing and extending role. Less accomplished skiers reacting to their ankles flex being largely taken away naturally use whatever will accomplish the task of tipping the skis. Since the knee can only flex a few degrees laterally before injury occurs, it's easy to see why hip angulation becomes a primary work around option. But lost in this is the idea that inclination is also an option. It's through the combined use of inclination and angulation that balance is maintained / created. For inclination to occur the pelvis and the rest of the torso moves over the skis in a pattern similar to how a metronome would move. When additional RoM is needed lateral body shaping occurs. But in either example the balance axis and location of the pelvis / hips dictates where the feet must be so the force vector we call the balance axis passes through both the feet and the core. You can move the BoS, or move the CoM but in the words of Ollie Larsson, "the net effect is the same". So it really circles back to the idea that regardless of your mental focus the entire body is moving in unison and simultaneously adjusting to create a balanced stance.
It's odd that you find that idea so controversial.