@Quokka I can imagine using it at someone's place who didn't have sauce separate from mustard so I could choose proportions.

Couldn't have used it as a kid - severe mustard intolerance, to the point of actual vomiting when socially forced to eat foods with mild mayonnaise. (Adults learned quickly to believe me when I said something made me sick!) Prefer to be able to have sauce sans mustard most times even now.