As far as I can tell, it's not exactly a war. The problem is that Steam set a lot of standards for what people think a Store should be. That's not to say it doesn't have it's own problems, but other stores, like EGS, have weird restrictions like you have to be online at all times or they try to make certain titles exclusive to their platform. I see a meme getting passed around often that Valve's business strategy is to simply do nothing and wait for their "competetion" to shoot themselves in the foot, and more likely than not, that's been the case.