Robert Dixon Phillips, a retired UGA professor of food science, was quoted in The Atlantic about the art and science of making good Southern biscuits.
In most of the U.S., available flours are made from hard wheats, which are higher in gluten protein. For this reason, their dough can trap carbon dioxide, which is why it would be used to make bread.
To make a good biscuit, “you want a flour made from a soft wheat,” Phillips said. “It has less gluten protein and the gluten is weaker, which allows the chemical leavening—the baking powder—to generate carbon dioxide and make it rise up in the oven.”
According to Phillips, biscuits likely developed as a Southern staple food because the flour necessary to make them was and still is made from the kind of wheat that’s farmed there.