I LOOKED AT IT HEAPS FOR MY OWN NODEL AND HAVE BEEN STARING AT FACES OBSESSIVLY FOR MONTHS NOW BUT I HAVE WORK ED OUT ( PROBABLY JUST INVENTING THE WHEEL AGAIN BUT HEY) THESE EDGES ARE ESSENTIAL FOR FACE TOO WORK WE ALL GET FOLDS ALONG THESE LINES AND YOU CANT MAKE THE FOLDS WITHOUT THE EDGES SO...
THATS MY 2 CENTS WORTH