Everything old is new again. This boarding technique was done back in the 70's/80's. I remember it was frustrating if you were in an aisle seat - by the time you got to board, there were no overhead bins left. It would be instructive to learn why airlines abandoned this boarding style before.
One more BTW - American is supporting Delta's petition, and United is worried that Hawaiian will also support it. IMHO, Delta's petition makes perfect sense. United's complaint is self-serving to say the least.
Dream on, United. Delta has never hinted if their request is denied, they will not operate flights to Haneda from either Portland or Honolulu. BTW, United has also not restarted flights from Honolulu to Japan - so perhaps Delta is onto something. United would never admit that.