It can be used for finding a sweet spot between Discrete and Loudness in the immersive space. If you have 16 channels in discrete and add more range control it will bring down the loudest channels, hence reduce the range between the loudest and the other channels. It makes the overall mix louder.

In the Loudness mode the relation between channels remains the same so the effect is that it sounds quieter with Loudness.. Having the ability to slide between the two allows a great deal of control for immersive mixes.