[throwaway9524]

I get the reasoning from your other replies. If Microsoft extends Win32 with some new API that cannot be reimplemented in Proton then Valve is screwed. So you want them to require a native Linux version from every game published on Steam.

However I really do not think Valve is in a position to dictate such terms. They have multiple competitors both in distribution and console space. Big names are already publishing on their own stores. Small indies can move to itch.io. Everyone else can switch to Epic. Steam Deck is already underpowered compared to recent Windows based handhelds. If it stops supporting Windows games via Proton then it is as good as dead.

I understand your idealism. But a step like this would kill gaming on Linux much quicker than anything Microsoft could do. Because Valve is the only big distributor even remotely interested in it. In contrast Epic is absolutely hostile to Linux. And they're the ones to gain the most users in case Steam fails.