In reply, I offer the view of the Bays from altitude. You don't really have to have an eagle eye to see thousands of Bays of all sizes spread across the landscape, all oriented in the same direction.
There is simply no way for these Bays to have formed in this shape and orientation from the burning of peat fires.
Undoubtably, peat fires have burned in the Bays at times, but fire did not build the Bays.