At 210 degrees we have hot water; if we add a couple of degrees and now we are at 212 degrees we have steam capable of moving a train.
Well brake fluid, depending on the type, can have a boiling point of 500 degrees to 800 degrees when there is no contamination. Now if we add some moisture, just simply added from years of temperature changes. Add some contaminates from the various related components, now the brake fluid boiling point is 300 degrees to 600 degrees. The idea of brake fluid is to be used as a hydraulic pressure agent, but when it reaches its boiling point it turns to a vapor and you lose your brake pedal. This is especially true if you are towing or maybe your vehicle is very heavy like an RV or motor coach, then your brakes have the ability to reach the boiling point very quickly. So regular brake fluid flushing is extremely important for correct brake performance. Another overlooked service is keeping the calipers and pad slides lubricated to keep them applying and releasing properly, saving fuel from releasing completely and saving you form overheating caused by dragging.