A better way to look at this is valve is trying to hedge it's self against microsoft. By creating an ecosystem of devices and software that's full open so they're not reliant on Microsoft. The goal of Valve hardware ISN'T to make money. It's to encourage others to build devices free of Microsoft that Steam can be installed on.
They have nothing to gain by being closed, and everything to gain by being open.
Steam has been an incredibly good steward of its position, but I fear for the day when capitalism finally sinks its claws into the platform.
Capitalism has nothing to do with short term greed.
Some CEOs are just too arrogant and think that optimizing for the short term won't hurt goodwill. That's their own failure. Capitalism says nothing about how a business should be run. It's merely defining the idea that humans who own things (capital) allocate their resources and keep the result.
Regulation can also break things if done incorrectly/poorly/inefficiently/corruptly.