Yea, I know, I just use Hue and Lighting for my ramp texture, while lighting is just grayscale. So Hue controls color while Lighting controls how that color looks in the shadows and in the light. I calculate Luminance from Base Color and use that to lerp between 3 different ramp textures, dark colors, medium colors and bright colors.
Me mentioning Luminance there didn’t make much sense.