[Color Calibration] Why do individual grey tab sliders change histogram for RGB channels equally?

[kofa (István Kovács)]

Have you already read

Introducing color calibration module (formerly known as channel mixer rgb)

Camera reference is a set of WB coefficients that make D65 light shot by this camera a neutral color. You can see that as the bare minimum for removing the green cast and ensuring the validity of the input color profile. It doesn’t work for DNG because they have their own built-in profiles and it needs special handling that is not coded in darktable now.

and
https://darktable-org.github.io/dtdocs/module-reference/processing-modules/color-calibration/
?