ya..true true, front contribute 70-90% braking...
but 10-30%(depends on car model) of braking force still apply on rear wheel when u step on the brake pedal..

In fact, most of the modern vehicle is advance now, u cannot tell the difference on normal driving what's t difference btw rear drum n rear disc!
the most significant difference...try this---> do a handbraking U-turn..90/180/360 degree ...pull the e-brake hard to lock rear wheel..easier to lock t wheel on Rear drum car..Dunno why??

for enthusiast driving n Look, i still prefer t rear disc..the brake pad on rotor clamp at the disc..
Imagine you have big rims, eg: 17" and super tiny rear drum..Not nice..