Man they need to up their offerings, i don't mind buying on non Steam sites, i purchased from Green Man, have Uplay but these guys need to offer more games.
I suspect Steam is telling developers that if you offer a game on Origin you can't sell on Steam.
Since 75% of all digital games sold are sold on Steam they have no option but to.
Origin is essentially the EA online store, lets be honest here.
There are a few games that cross over to both, such as battlefield bad company 2, and Crysis 2.