thats where all the weight shifts if youre driving a big short pickup with soft springs and highjackers. not if you are driving a low stiff sports car. the rear brakes are wery much a part of stopping distances... ie do you think f1 cars have all the brake preassure on the front wheels? if you do not, why do you think they are not routing all the preassure up front?
a lower stiffer car that dont nose dive to much when braking would benefit from more rear brake bias. cause the rear tires have more grip that could be used during braking.