The Giannis step-through controversy perfectly shows why we need to understand the gather rule. When players stop the ball's momentum - whether with two hands OR by controlling it with one - that's your zero step. Everything after that is one-two.
People get confused thinking you count from the last dribble, but that's not how it works. The gather is when you gain control and stop the ball's forward momentum. Giannis does this beautifully: stutter steps while dribbling, gathers on his left foot (zero), then right-left for the finish.
This is textbook legal footwork that looks like a travel in slow motion but isn't when you understand the rules properly.