The subjective notion of quantity refers to the speaker's subjective evaluation of quantities and is a subcategory of the quantity category.
But more than that; "utility" is not a thing or an entity; it is simply the name for a subjective evaluation in the mind of each individual.
Utility is a subjective evaluation, a ranking by theindividual, and there is no measurement, no extension, and therefore no way forit to be proportional to itself.