The theory is that.... they''re supposed to be. It makes logical sense. The same way that it made logical sense to people in the 18th century that you should drain the bad blood out of people who were sick. No one seems to have actually been able to prove that double-ended boats are easier to control in a heavy following sea. So if you believe it to be so, it will be for you, and you can sail happily with a tiny cockpit, no lazarette and nowhere to mount your grill
, self-steering, and MOB gear. The proof would involve the same helmsman taking the helm of the same double-ended boat and a transomed boat at the same time, so he could tell which was easier. Quite a trick.