Many games that fall into the free to play category also fall into the pay to win category -- which is to say that if you want to be able to play well, you'll wind up forking over some cash. It's a big frustration with free to play games which can easily wind up costing just as much -- or even more -- than games with an ordinary pricetag. So while we wondered whether we needed to sink money into buying more Hearthstone packs, we were glad to see Polygon had done a detailed examination of the advantage you get from buying cards in Hearthstone.
Though anyone interested in the economics of it should definitely read the entire article, the end result is that because there are many options to earn in-game gold to buy packs -- and because the best decks aren't necessarily built with all epic cards -- with some patience a casual player will catch up with a big spender. But, still, opening pack after pack of cards that has an appeal that has nothing to do with economics.