markbarendt, you are looking at a print, not the negative, there isn't less detail, but less contrast. But on top of lower contrast, minimum opposing density rises, so the colour separation is also smaller.
The best saturation/contrast is around mid tones. If it was such a straight line, you wouldn't need to raise exposure for things below mid tones. And I wouldnt see reduced contrast and saturation above mid tones. There is not much saturation in white to lose.
With a thinner range, grain contrast increases if they are displayed at the same contrast as a broader range negative.
Blue dresses are a more pure (saturated) colour than a chocolate Lab to begin with, and such light dresses would be around or just above mid tones, and a chocolate Lab below it by the sounds. There is no saturation in white to lose, contrast isn't detail, you can have more detail in low contrast object then you can in high contrast, and also vice versa.
"Yes this can be done like the zone system or a push."
You mean a pull.