They’ve made Linux gaming a thing. And there where no players there either. So I do not believe that is their actual reason.
The actual reason is that Valve does not want to be beholden or locked to a corporate entity like Apple or Microsoft. They would be very dependent on the whims of those companies.
Linux gives them a platform where they know and can influence it’s future.
I think Netflix would simply see that as a nice extra benefit. But the main reason is to “stick it” to the writers/actors. Without incurring the wrath of customers for the price hike themselves, they will just point their finger…