The word "pleasing" and thus the subjective element come from the dictionary definitions of "harmony." If we eliminate that element and concentrate on objective relations of the fitness of certain parts, "harmony" becomes a vacuous weasel word. If an asteroid smashed into our planet, killing all life, the parts of that process, too, would objectively fit together. The support and the dependence here amount to mere causality. All causes and effects fit together. Some are more pleasing than others, and harmony is found only in the pleasing ones. Some note combinations are pleasing to the ear, while others are discordant. So the subjectivity isn't so eliminable if you want to use the word "harmony."