The thing is that you can no longer generate gold from that, the way you could before. If you SELL the things back, you are not ahead of gold (the old exploit was indeed that - you buy insane amount of a single card, then you start selling, since the selling price was always going down by 10%(how its supposed to be), but the buying price, when the merchant is out of stock was going up by 100% after each copy, you could generate infinite amount of gold). That not the case anymore.