no, there is not a net shortage of food, system-wide. It is easy to spot a naive answer because the vast productivity of basic foodstuff is not widely known, nor intuitive.
I'd refrain from calling people naive. Farmers would call your approach naive as they know that every promile of productivity counts and can make or break their investment. As you said, this is very unintuitive and it's hard to imagine how much can a tiny increase of productivity at the base level change at the output - but it really is a lot.
agree, that is why I wrote "the answer is naive", not a quality of a person writing the comment.