The biggest issue with imperial recipes is the constant use of measures by volume. If everything was in weight ounces it would be alright, but a lot of recipes insist on measuring solids by volume, like a cup of flour, a teaspoon of sugar etc, making them a lot harder to replicate consistently. My flour could be denser, my sugar could be finer, if things were measure by the actual mass such things would not matter but instead I have to fill a cup and pray to the gods that my cup of Ecuadorian flour has the same density as the one on the recipe (it almost never is)