so I think, as I am typing this, I am heading towards believing that it is better to include everything and to give reasons for why they are left out mostly in the categories of photo shop or seemingly low effort trolling.. rather than "that ain't no pizza"... ... but if the conclusion is that the submission fails to fit the "definition of pizza" then that would be better to state it, rather than to "ignore" it.
I agree with you but the word "pizza" does not need to be defined as it does not need to be defined as "water" or "coca cola" we all know how these drinks are. If I order a pizza, the waiter must bring me a circular pasta cooked in the oven (preferably wood-fired) with a layer of tomato on the surface up to half a centimeter from the edge covered with mozzarella. This is the basis. Finally, you can season it with some ingredients such as ham, mushrooms, peppers, salami, artichokes, etc... but any type of strange dough cannot be defined as pizza. For the dough you need water, flour and yeast. It's that simple and I don't expect a regulation to define what a pizza is if the contest plans to cook one.