Here is an example of the advantage for post color corrections, preparing 3d rendered images for offset printing is equally challenging where practical experience is required to achieve the intended result, the reason is that RGB image is meant for display device which is the spectrum of light while CMYK are pigment ink which require white surface to reflect colors from. So, it is four colors vs. the rainbow.

Knowing that CMYK can never reproduce the kind of colors we see in RGB, we can only improvise, meaning if you care enough for a better looking picture.