> They have absolutely no connection to the matter at hand. Since foo is often used before bar, you would think there is an ordering between the two but there doesn't have to be. They are hard to pronounce and easier to confuse.

I couldn’t disagree more. The entire point is that the variables are disconnected from the matter at hand. They’re widely recognised as placeholders, single syllable, distinctly pronounced from each other, and have an implied ordering.