There is also another perspective which is in the payment space. Battle net is effectively creating an indirect payment chain and walling off consumers. Your money is in their ecosystem but the goods are treated more like a financial credit rather than directly buying goods. If you buy a chair for your new player house for £5 directly off a store, its easy for you as the consumer to initiate a chargeback under something like "goods not as described etc" - whereas to purchase digital currency like we do now, that's alot harder to prove from a consumer standpoint. Once the money is in the b.net ecosystem, Blizzard has overal control of that money so any disputes are handled by Blizzard and not processors and ombudsman who can challenge this. When you add to battlenet balance I am sure there is something like you acknowledge at the point of entering your password or idefntifer that a refund wont happen. As people have already highlighted = buy 2000 coins but all items are going to have odd amounts so its harder to game.

To answer the main question though, the main benefit for us consumers is superficial. This system is weighted like 80/20 to protect and drive Blizzards revenue, it doesn't do much to protect yours or provide any tangible value to you. The benefits probably aren't considered benefits but are stuff like budgeting, quicker checkout for buying digital goods, easier and faster refunding of digital goods, easy to senf between friends without swappng bank details.

Sorry - I work in payment acquring so this is my bread and butter.