I think that would enable tearing for all windows no matter what they are as long as they are fullscreen. I'm not sure that would be desirable. Although I lack the knowledge to judge this. So sure, that is an option. I would really like to restrict this to games only, though.
Thank you, I will add this to my Sway config (and change it for Hyprland as well).
I usually don't use gamescope. So I'm looking at the first of your two examples and I'm not sure I follow. The class is "steam_app_1066890", right? The number at the end should change with every game installed by Steam. It's a unique identifier Steam seems to use for all the games on Steam. So how does the class stay the same for your games? And thanks for noting that allow_tearing isn't in any current release at the time of writing. It's the same for Hyprland. I should have mentionend that.
I agree. It's not only placebo, though. I will gladly admit that I'm not very sensitive to these things and can't immediately tell if something is wrong. I had this experience and I even had it in reverse. After days of playing very badly I realised Sway all of the sudden was running my monitor at 60Hz. After fixing it with kanshi (which I didn't have to use prior to that) everything in game was so much easier.
You really put it well: A friction that you didn't even know was there.
In general you are right. We want to avoid screen tearing. Gaming doesn't have to be but can be an exception. If you were to play some fast paced game like a competitive shooter for example. Then permitting tearing would reduce latency. In my case, I can feel the difference when tearing is allowed in The Finals. It is easier to follow the target with your crosshair. That doesn't mean everyone would feel the same. Nvidia's driver version 560 also got released recently. That might have something to do with me perceiving the gameplay as more smooth. All I'm saying is, smooth and enjoyable gameplay not only depends on a high fps count. Framerate, frame pacing, and latency are all factors in this.
Oh, and by the way. this doesn't at all mean that one is going to see/perceive any screen tearing when this is enabled. I haven't noticed any at all. I'm sure one could find some when one was to go and really look for it. I'm simply not too sensitive about that stuff.