I don’t defend P2W aspects, not at all. Pay to win is the gameshop offering items directly for sale that are anywhere from OP’d to nukes from orbit, and may be offered in game, but with a 300 week grind. The Blizzstore doesn’t sell gear (yet, with the way they have been going, I’d not be at all surprised if they did) so as such, it isn’t P2W in a traditional sense.
Gold has always been available for cash, from 3rd party sites. Some people have always bought gear. Those people were usually bad(They certainly weren’t winning. Now gold is available directly from Blizz. Officially sanctioned account safe gold. It wasn’t pay to win back then, and it isn’t now.
You can buy gold, get gear, and go PvP. You might whack some fresh 120’s, or what not in World PvP/BG’s. Meet anybody that knows what they are doing and you are going to get whacked/greasespotted. Same goes for PvE. You can buy the runs, but you didn’t earn it and it shows. Not winning. More like clowning. So it isn’t even close to P2W, more like Pay to Clown.
I can go and grind moosebungholes for 200 hours and sell them for gold, which I can convert into +9000 mythic runs. I can get Ilevel 5000000 gear, and have a raider IO of 999999. I still don’t have the skills for that run, nor do I have the skillz in PvP to be leet. Same critter, different method of obtaining it.
edit:The cash shop just offers a easier method for people to convert cash to gold, and bypass the moosebunghole grinding aspects of the game. When they offer the Stick of Noobwhacking, on hit effect of killing anything you hit instantly, that is P2W. Until then, no.
PS One Stick of Noobwhacking for sale, only $29.99 plus shipping and handling and tax.