Kotelnikov takes a little effort to wrap your head around because it's fundamentally different from most other compressors. It's actually two separate compressors, one having a peak detector and the other an RMS detector. They share a common attack value but each has its own release time.
Balancing the two compressors is accomplished via a "Peak Crest" knob. This more or less determines your peak-to-RMS ratio, otherwise known as the crest factor. Crest factor is actually much more involved than that, and is greatly affected by attack time, compression ratio, threshold and knee shape. But the "Peak Crest" control does let you moderate the compressor's effect on peaks, depending on whether you want to have a crisp, punchy mix (high crest factor) or just a very loud one (low crest factor).
Placing a compressor on the master bus normally has the effect of lowering the crest factor by raising average RMS (and perceived volume). Up to a point, lowering the crest factor is desirable for most genres. It's what's often referred to as "gluing" the mix. But just as you learned by assembling plastic model cars and airplanes as a kid, there is an optimal amount of glue, beyond which you just get a gooey mess. Too much glue compression will also result in a gooey mess of a mix.
Granted, sometimes that's exactly what you're after: a loud master at any cost. Kotelnikov makes it easier to dial in just how much of the micro-dynamics you're willing to sacrifice in the name of loudness.