I specifically phrased it “could be” as people tend to believe there are 3 preferences, Mac, Linux and Windows. Linux is not one user experience, it could work exactly like your favorite OS. In the face of SteamOS already being a viable option for the average gamer as Valve is basically strong arming it to be, on Steam Deck you’re not exactly doing PC gaming any good deliberately installing Windows on it. SteamOS just works.

I also think you’re very misguided in thinking it won’t have any return to Valve. Microsoft has to be looking at Google Play Store and whatever the Apple Store is called with a lot of envy with how they’ve managed to lock the entire ecosystem under their stores. This is the end result for Windows as well and its likely anti-competetive clauses are a very bad sign for a company like Valve. Looking back I’m actually impressed just how far back Valve saw this happening. Decoupling PC gaming in its entirety from Microsoft’s vendor lock-ins is in the best interest of all of the companies in the gaming industry, but it takes a rich private company like Valve to start doing the hard work for long term benefits instead of always chasing the short term profits.

Even if tomorrow Microsoft launched something that pulled ahead of SteamOS, it would still be in the gamers’ best interest to stick with the open platform. With a consistent, large userbase on an open platform it will eventually eclipse anything Microsoft could ever muster.