With corruption it was most definitely pay to win. One BoE could double your dps.
Generally its just kind of an indirect pay to win. You can buy tokens, buy carries in game and buy a few powerful BoEs off the AH.
I think people think if you aren't buying an item directly off the cash shop its not pay to win, but all Blizzard has to do is set up a 2 or 3-point transaction system that accomplishes the same thing for them and they get to dodge any major controversy.