For a few years before I eventually got a Steam Deck, I played a lot of games that I bought outside of Steam, and over the past decade, the experience of doing this on Linux has massively improved. Plenty of their improvements get upstreamed to Wine, and there's nothing stopping you from obtain proton (or even one of the various unofficial tweaks of it) to run games that you don't buy through Steam to get the benefits that aren't upstreamed (or haven't been yet). The article itself mentions that they've implemented a driver for Mesa that has equal or better performance on ARM than the proprietary one from Qualcomm.
It's not clear to me what you're attempting to convey by saying the Steam Deck being the only product they have that supports the open source vision. The Steam Deck is the only new hardware product they've had since 2019, when they released their original first party VR headset that presumably is being replaced by the new one. Other than that, the only other hardware products they've ever worked on were earlier headsets made by other manufacturers or the previous iterations of the other two products announced alongside the new headset. From that standpoint, you could make a credible argument that the only product they even have right now that benefits from the open source work they've done in the past six years they did is the exact one you say supports this vision.
Exactly they have no track record so the benefits remain to be seen how gaming improvements to Linux are advantageous to people who use FOSS beyond paying Valve for Steam DRM’d games without requiring a Windows license.
I'm not sure what you're reading into what I said, but to reiterate: I've been seeing benefits personally from their work for years playing games that were not obtained via Steam. It's unclear to me why you think this is "exactly" the point you're making, because it's quite literally the opposite.
Because games are entertainment and this technology is not necessary for the betterment of humanity or enabling some kind of real technological progress, therefor it only really benefits who? Valve and really only in the short term. Once the contributions back are good enough, people will start to use the stack to cut Valve out. There for Valve only has incentive to contribute things that make their products great. If you enjoy playing older games on Linux because of Valve, that is only a side effect of the current efforts.
No, I still don't have any idea what you're trying to say honestly. At first I thought you were trying to say that they didn't contribute to open source in a way that actually helped anyone outside of themselves. I stated that it definitively helped me do something I already had tried to do sometimes but would sometimes have issues with, and no longer do in large part because of their work. As best as I can tell, you're essentially arguing now some combination of an assertion that it's impossible by definition for a company's open source contributions to benefit anyone else in the long run (which feels pretty reductive, like the economics arguments that everyone always acts purely rationally, despite the fact that plenty of people quite often don't do that) and that because it's only software that helps running video games, it can't possibly be beneficial to humanity in general (which independent of whether it's accurate feels kind of irrelevant given that the original proposition from the parent comment was that they did care about that and therefore wanted to support it financially).
It's not clear to me what you're attempting to convey by saying the Steam Deck being the only product they have that supports the open source vision. The Steam Deck is the only new hardware product they've had since 2019, when they released their original first party VR headset that presumably is being replaced by the new one. Other than that, the only other hardware products they've ever worked on were earlier headsets made by other manufacturers or the previous iterations of the other two products announced alongside the new headset. From that standpoint, you could make a credible argument that the only product they even have right now that benefits from the open source work they've done in the past six years they did is the exact one you say supports this vision.