Perhaps we should think of the rear brake--in most situations--as more of a "drag" brake--to slow things down, than a "stopper". The front brake is much more useful; I've "tail whipped"--with a disc brake!--by using too much back brake, even in the "loose stuff". Once in the direction of traffic. During rush hour! I was lucky to NOT go down!

Also, use the rear brake to (carefully!) slow down when retaining full steering control (technical terrain, tight traffic) is essential; using the front brake in this case will impede steering or (almost) "jam" it entirely. Foresight in dealing with the conditions/obstacles present can minimize this problem--and the use of the rear brake. Same with "emergency stops" anywhere. These "dual-brake-jammer-sessions" too can be minimized by simply paying attention to what you are doing!

To sum up: Thinking ahead=foresight=safety in braking!