Drawing power causes voltage drops; I suspect what they're saying is that a degraded battery under heavy load will momentarily drop from 40% to under cutoff threshold.
Large voltage drops under load are typically an indication of a bad cell or battery. You could argue this is beneficial to the customer but Apple is hiding the fact that they're doing this. Why?
I recall when they switched to non-replaceable batteries in MacBooks, they boasted how their battery lives were the best and would last x years. Is this how they did it?
