In the page you linked to one finds the HLS model visualized as a cylinder = 2d-circle x height. (A round cake )

While height is (L)umidity, does the distance to the circles center represent (S)aturation.

The axis of that cylinder, the circles center (S=0) is the gray-scale, with black at the bottom (L=0) and white at the top (L=1) and belongs to all "colors" of that wheel.

I.e one point on the wheel represents all colors in the rectangle formed by axis and angle. (The side of a cakepiece)

Crazy!