In 8-bit[1], each time you play with anything that changes the response curve (be it Levels, Curves, Brightness/Contrast, Hue-Saturation, Color Balance, and a whole bag of scripts and plugins)…) you lose colors (and the more pronounced the effect, the more colors). Curves is the only tool that lets you do the whole effect with one single tool usage, therefore minimizing color loss.
[1] This is also true for larger bit depths, but much less perceptible.