Dirt and contaminants getting between the rubber cover and braid, accelerates the rate of wear on the assembly and braid. We don't even allow cracked covers on any of our hydraulic systems. And usually, is the outside cover is starting to disintegrate, the inner is the same age. Which leads to wear and contamination of your other brake parts. On a hydraulic system, even more critical for all the valving involved. I use the comparison because brake systems are a simple hydraulic system.
