Chmetz is “b’mashehu” which is even a speck. When the flour and water is mixed, is it not possible that a minute speck of flour remained on the outside or inside of the dough? This speck of flour can later become chometz if used gebrokt!!
Ask any lady who bakes challah if it is possible that a speck of flour remained and did not mix into the dough!!
I have no no disrespect for the minhag. But I will happily disrespect your unbelievable and idiotic thinking that it is pashut.
If it was such a real concern like you say, it would be assur m’dina.