...If Stardock is selling Fallout: New Vegas five or ten bucks less than Steam does, they would make tons of money.
Stardock and Valve don't control pricing for any of the titles on their services apart from their own. Impulse can't undercut Steam's prices to win any portion of the market - it has to offer the games and products on its services at the prices Stardock is told to offer them at and to the regions that they're told to sell them to. Valve and Stardock might be in a position to arrange for a weekend sale here or there, however they can't just decide to sell someone elses game for $10.00 less than every where else.
No one is preventing other platforms from offering Steamworks titles except themselves...
If this is your opinion, then you clearly have no understanding of the market forces in play and the eventual outcome that systems like Steamwork's are designed to ensure; namely, everyone buying and playing PC games through Steam with no exceptions. I've covered this a million times, so I'll sum it up quickly; selling a Steamworks title makes your customers Valve's customers regardless of where or how you sell it. Period.
Impulse, Direct2Drive & Co tried to force publishers to stop using Steam and failed...
They didn't try to force anyone to do anything, they simply replied to Valve's anticompetitve software in the most logical manner possible: not carrying it. And they didn't fail; they haven't even started to fight back yet. Impulse::Reactor, Stardock's answer to Steamworks, doesn't launch till August. It offers the same service as Steamworks without requiring the Impulse client to be installed or running, unlike Steamworks which requires Steam installed and running at all times. Valve doesn't own the PC Platform, however it's certainly trying to and what they're trying to do with Steamworks would be considered a Hostile Takeover in the corporate world. They're forcing Steamworks onto as many computers as possible by shackling it to high-profile games like Fallout: New Vegas and Civilization V in what is a text-book Trojan Horse business strategy. This strategy has a single goal: to force out your competitors and assume complete market dominance in a situation where you can't do so in the typical manner, such as offering a competitive service. You steal your competitors customers. Considering Valve are the leading Digitial Distribution service already, this underhanded business practice speaks volumes about where the company is headed.
Steam works great, and I own several games on their service. However, Valve have some of the worst customer service in the entire industry and have documented cases of banning people for asking why they were incorrectly charged twice for a game. And when Valve ban your account, they have a nice little clause in the EULA which states that they will never unban your Account and will not disclose the reason for doing so. Every game, every piece of content, every update, everything - gone. They nearly equal EA Games in terms of going out of their way to fuck over their customers. Valve and it's service simply doesn't work well enough for me to willingly want to turn my computer into Valve's version of the Xbox, where they control everything from update release schedules, regionally availability to DLC pricing and have the ability to disable my entire collection of games.