I've gone back and forth on this over the years.
I'm glad 15 minutes has been your experience. For me, who does not use Windows at all for other purposes, it has taken considerably longer than 15 minutes to figure out where all the settings are to disable and uninstall annoyances. As somebody who stopped using Windows in the XP era, none of the settings are where I remember them being more than a decade ago when I last seriously used that OS for anything.
Since I'd only use Windows for gaming, there's also a non-trivial amount of time spent rebooting into Windows, and the slight annoyance of having to either keep a remote desktop tool open or a laptop nearby if I wanted to do something else on the computer other than launch a game.
And since my gaming computer is custom built, there's also a non-trivial expense of purchasing a Windows license.
The one compromise I have considered is keeping a dedicated Windows gaming PC in a closet and using Steam Link so I can actually play the games on my preferred device, whether it's at my desk or on the TV. It doesn't solve everything I mentioned above but at least it gets closer to the set-it-and-forget-it approach you've taken.