"If your recipe calls for... "
One of my personal recipe bugbears is actually not just using unintelligible (to me) weights such as pounds and ounces, but the use of weight at all, even grams. I have kitchen scales, which have to be set up, set to the correct system (metric v imperial), and recalibrated if you use a different-weight empty container.
Volume is simply much easier than weight. i don't care if 'cups' isn't in a recognised system, it's much easier to work with volume for both fluids and powders, what's important is the ratio, and the volumes can be simply adjusted by using bigger / smaller cups instead of having to recalculate weights on the fly.
I do draw the line though, at the recipe that demanded 'a cup of butter'