Saying there is no competition to the consoles store would be silly though. The xb1 store is competing with the ps4 and vice versa. And right now both are being undercut by physical sales, so they have to find a way to fight that.
Where is the competition on the Xbox live store if you only have a Xbone? The PS4 store isn't a competitor in this scenario at all as you can't exactly go and buy a Xbone game on PSN... Retail copies are technically the competition but what if you want digital only?! You have one choice, pay whatever Xbox Live is charging.
Steam is very different in this scenario as games can be bought from multiple sources and the key used on Steam itself. You don't have to buy the game through Steam to use it on Steam.