High-output engines benefit from more efficient oil cooling than the factory system can possibly provide. Our stock parts are simply not up to the task of controlling the huge heat that a hard-driven engine can produce. This is especially true for rally, street, and other motorsports use where air flow is limited but output is high and sustained for long time periods.
The stock system transfers heat from the oil to the engine coolant and vice versa depending on which fluid is hotter. This may help or may actually compound the problem. Oil lubricates best when kept between about 180° and 212°F. Below this temperature, the oil isn't hot enough to burn off harmful contaminants. Once above 230°F, it thins out and oxidizes (i.e. "burns") making it significantly less slippery. Thermostatic plates automate temperature control.