It would be more accurate to say Origin has sales, they exist but I wouldn't call them great as there really haven't been enough to compare it to Steam which has hundreds under its belt at this point.
Except Origin hasn't been around for as long as Steam so there's no way it could have had as many sales. In the short period that Origin has been around, there have been a number of great sales. The ability to get BF3 for free by pre-ordering ME3, for example. Origin was the first to offer Arkham City for $25 as well and that's the reason why I installed it.
As I mentioned before, you don't have to be running Origin to run the games that don't require it. The interface and features don't really mean much when you don't have to use them. You log in, buy a game, download it, install it, close Origin and that's it. You never have to run it again unless you buy another game. This alone makes it better than GMG's Capsule, which must be run every time you play any game and requires regular re-authentications. It's also better than UbiDRM, which has no benefits whatsoever and must be run with every new Ubisoft game.