My guess is that there are attempts to keep things like ‘colorfulness’ more persistent , and/or the luminance/brightness of the colors. As in , there is ‘perceptual’ studd going on.
And then all colors don’t respond the same , which causes weird results if you are working on images that are computer generated.
The color calibration comes to mind , when people expected a pure channel mixer but that’s now how it works.
More and more parts of Darktable are meant to be used in the context of a light capture , not computer RGB values as in an ordinary image. Trying to use Darktable for things normally done in an image editor can sometimes cause weird results .