On the one hand, it's good that carriers experiment with different approaches because there is a fine balance between efficiently loading an aircraft and customer satisfaction. On the other hand, when the USS boarded F and then from the back of the aircraft with no Zones, it took somewhere in the 12-15 minute range to board a full 319 or 320.
There is only so much that "priority" matters beyond those who think that they are important so want to be made to feel important. The sole reason to board early is to get your bag in the OH. If you come before the OH's fill, you are fine. If not, that's bad.