pdq - "This shows that these folks have (some) other reasons for their picks, and those reasons (the other ones, that is) have little to do with singing ability."

I added the stuff in brackets to make your statement a little more moderate, pdq.....but I think you're basically right, because that's the way it usually is with those kind of lists. They reflect the cultural viewpoints and prejudices of the people who contributed. They are only a fragmentary view of reality, like a snapshot taken out of one window that claims to show the entire neighborhood.