In my three books on ski technique the inside foot is always a major focus.
My first book we self published n 1997. No one had ever heard of tipping the inside foot at the time, many coaches still don't.
Here in slalom, Mario Matt 34 years old, converted to a narrow stance, since his earlier days on the world cup and tips and holds the inside foot back. As soon as the inside foot slides forward you lose speed and edge carving. Pushing the inside foot forward is a braking movement. It often shows that the skier has fear of his speed and is desperate to stay in control.
Marcel Hirscher is the "King" of controlling and using his inside foot. He holds it back the longest in the turn, even below the arc or the gate.