I don't really play multiplayer games other than a self-hosted Minecraft server, so for me the SteamOS experience (using Jovian on NixOS) is strictly better than what I had on Windows. A lot of games from the late 90's/early 2000's have trouble running on modern Windows but work fine with Wine or Proton.

I've been utterly astounded by Proton in the last year. Nearly every game I have run has run just about perfectly, often better than on Windows, and I'm able to play them with an Xbox One pad no less.

Valve absolutely deserves a lot of credit, but I do think that the constant effort from the Wine people should get a lot of credit as well. Wine has had constant progress for three decades, with every release getting a little better. I haven't worked on it, but I suspect 90+% of the work with Wine is figuring out all the weird edge cases that have popped up on Windows throughout the years, which is often slow, tedious, thankless work. Valve did a lot of work but there's a reason they opted to improve Wine instead of writing Proton from scratch.

The problem with Wine is that you most know what libraries to add, etc. PlayOnLinux automates that process somewhat but still very manual.

Steam Proton makes the whole process painless, you only select which Proton version to run, and that info can be obtained from ProtonDB if you encountered any issue, it is beautiful.

As for Linux, even emulators works like never before. I could never get PS4 emulator to work on Windows, I got PS4, X360, GameCube, and a bunch of other emulators running on Linux like I couldn't believe it.

You can do the same from within SteamOS itself, you just install an app, select the emulator and you ready which is far easier than me doing this from from Linux.