There is one company here in Argentina who is selling a game through Steam. It's a rather bad game (so no "good games only" filter I guess) from what I've read sadly BUT they have it there, and no other company involved besides Valve of course.
If you are talking about War Z,
No War Z is russian I think. I was talking about "Bunch of Heroes" from NGD Studios. That one us published through Steam, and their MMORPG is called Regnum Online, which I played a few years ago and is pretty fun but lacked in content (probably fixed that up by now), art is pretty WoWish though (it was developed when WoW was the thing to play after all).
I don't agree about War Z though. The developers did have experience with previous games (and actually, seems that most of their War Z assets are from previous games) and there are waaaaay more fishy things around the whole issue that I'm comfortable with to think about it as an "honest mistake". But that is offtopic.
And about Greenlight. Well yeah, I mean, the people that vote are the same people that buy CoD each single year. We're all to blame for that, even if we like to think we do are the "PC Gaming Master Race". And I've seen the worst of Steam users with the whole Skyrim Workshop issue (for example, modder launches mod using SKSE in Steam, gets a shitstorm for being a "lazy bastard" who wont make the mod a standalone thing, obviously ignoring that you can't get some functionality at all without SKSE).
I guess its a faith thing. Its bad sometimes but it can get better once the community gets accustomed to it and, after a few mistakes, can mature enough to efficiently choose what games should be Greenlight'd and what games shouldn't see the light of the day.
Greenlight (and Kickstarter) are a very recent thing (as in, they become popular recently), and as the Workshop, it will take time until the community gets wiser about it. Users will be childish about it because the whole thing its in its infancy. Like any other online community, give it a few years.