In the case of micro transactions, why should a store front get part of that sale? I hate Microtransactions, however the store front is not developing the new content, so why should they get a cut of the costs of loot boxes, extra currency (Not sold on their store) or subscriptions (not sold on their store)?
Then why should Steam or any other platform carry a "free-to-play" game like Fortnite? And by "free-to-play" I mean a game that one survey found the average player pays over $85 on microtransactions? Out of the goodness of their hearts and at a cost to them?
The real problem is this...
If 12% were truly realistic, some other storefront would have already tried undercutting the market at 25% or 20% and succeeded. This is the basis of free market economies. The idea that prices set themselves to fit supply and demand. The fact that 30% became a norm means that this is the price that works. And even at 30%, many online retailers have gone under which proves the point.
For someone to swoop in and claim that online retailers are making 2.5x too much is just hard to believe. Especially from someone who is becoming such a storefront. What did your mother tell you about deals "too good to be true"? That there is always a catch?
The catch here is likely one of 3 things...
1) The first one is FREE... Join us, the first month is free (or cheap). I hope you remember to "unsubscribe" before we bill you for next month. Or in other words, they have no real intention of maintaining a 12% cut. They are luring developers to their storefront, hooking them. When they raise the price, developers then have to worry about angering their customers who "bought in" to Epic in order to leave.
2) They are planning to make their real profit elsewhere. Selling client data; directed advertisements; or maybe their real goal isn't the storefront at all but a negotiation tool to their endgame to get a better rate for their games in other stores as they fold the storefront soon after.
3) 12% is their cut but with far more qualification than a normal storefront and 12% vs 30% is just an apples to oranges comparison and thus mostly a marketing tool. Or in other words what they call 12% is in actuality closer to what Steam or GoG or Humble call 30%. That would also explain why most of the games aren't any cheaper for the consumer.