I hear what you are saying, and being dangerous they would install a breaker that was not rated for the voltage to neutral of the manufactured phase and the piece of equuipment the installed would be manufactured and listed with the voltage to neutral also allot lower than this installation would be. I think the requirement just from this standpoint is smart.
Otherwise placing single phase loads on only this line may have a major adverse effect on the manufactured phase of some equipment. Why not just require the products main listing treat all products the same and avoid the dangerous person per chance they read the installation instructions.
