Kinda silly, in a high school cheerleader rivalry, way.
Seriously, who gives a shit what shape someone’s license plate is. Neither American or European license plates are superior. They’re just different, and how good they look/fit depends on the car they are.
In many cases, American license plates ruin the look of bumpers on European cars, even if they come in matching colors, simply because the plate areas were designed to accommodate the sleek plates, EU uses.
The DMV should just allow people to choose the fitting shape of license plate, and put an end to the whole nonsense.