Borntoski, your car analogy is pretty good. It gets to the "core"
of this movement philosophy.
It's really about a shift of focus. We look into the future, and from experience we know where our CM will need to be to support the type/shape turn we're about to make. We therefor make taking our CM to that location our primary movement focus. The lower end kinetic chain movements are merely supporting cast low end kinetic chain movements that enable us to accomplish our core movement focus. Bottom end kinetic movements are not something we strongly focus on, they just kind of get auto recruited in the core focused movement process.
Of course, in reality, those base kinetic movements do need to have attention directed on them at some point in the learning process. They need to be refined to best support the overall process of making a quality turn, and to ensure we're allowing the core to move as we desire it to. But this focus on the movement of our core can be a useful tool for keeping core movement harmonious with the tipping of the skis into a turn.
This is what I believe JASP means by "Contemporaneous connectivity". Everything moving together. The core moves in harmony with the tipping of the skis, keeping it always in an ideal position to resist the turn forces as they emerge. The core never has to play catch up, never gets left behind, as can happen when focus is placed on lower end kinetic chain activity. Low end kinetic chain focus can result in a sequential movement pattern (first tip ankles, then tip boots, let this pull CM into turn). This is the catch up pattern I spoke of.
And the bigger problem with a feet up focus is that it can stall somewhere before core movement occurs. You see this all the time on the slopes. The skis are on edge, but the core is still over the feet. This is a bad position, a weak position, a dangerous position, and it can block higher edge angle development. Focus on the core tends to eliminate sequential movements. It gets everything flowing in harmony and keeps the core from getting left behind.
It's something worth experimenting with. In the least new focus strategies help refine the ability to focus in general, and intensifies our awareness of what is happening in our default movement patterns.