Black point compensation (didn't hear of it before, just looked it up) seems to be aimed at increasing detail in dark parts of photos where several different co

Black point compensation (didn't hear of it before, just looked it up) seems to be aimed at increasing detail in dark parts of photos where several different colours get mapped by the colour space conversion to more or less the same printed colour. It does not seem to be a method of saying RGB(0, 0, 0) should get mapped to CMYK(0, 0, 0, 1), no matter what the colour profile says. A designer told me that RGB black is darker than CMYK pure black, thus the need for a mixed colour whenever you start with RGB instead of using CMYK from the very beginning.