With the widespread support for Steam/Valve on this forum because of their contributions to making Linux gaming easier, I'm now confused as to why people here are using Linux in the first place.
I personally do so out of support for FOSS software, the customizability, and actual ownership of software, which I thought were most people's primary reasons for using any Linux distro. Steam seems antithetical to all of these. The software in the first place became popular as a form of DRM, and it gets publishers to use it for the allowance of DRM on the platform. The Steam client has the absolute minimum customizability. Your account can be banned at any point and you can lose access to many of the games you have downloaded.
Whenever I game on Linux I just use folders to sort my game library and purchase any games I want to play on itch.io or GoG. On my Linux PC I stay away from clients like Steam because I want a PC that works offline, and will work if all of my accounts were banned. It's more of a backup PC.
Since Steam has every characteristic of Windows, 0 customizability, DRM, plenty of games that are spyware, I see no reason to really not use Windows instead for the much easier time I can have playing games.
Yes, I prefer many of the features of Linux distros, but using a client like Steam defeats the purpose of them. Ridiculous storage requirements due to unoptimized dependencies, having to have a background client running for some games and wasting resources on doing so.
So, why use Linux and support Steam, or use Linux and use Steam?
I disagree with your implication that using Steam on Linux makes it pointless to use Linux; I think that it is always better if you are able to replace some proprietary software in your life with freedom-respecting software even if you may still be using other proprietary software.
I’m not sure if you’re aware of this, but the FSF does actually acknowledge that replacing all of the proprietary software that one uses can be an incredibly disruptive, difficult process, and they encourage users to embark on the journey of complete freedom one step at a time - check out their Freedom Ladder campaign.