It’s so LFC works properly. If there isn’t a large range to work with, you can end up with gaps where VRR doesn’t work, causing stuttering or tearing. LFC is needed in general because you want VRR to still work when FPS drops below the minimum frame rate. And while it’s more of an issue with OLED displays there can be negative side effects such as flickering if the display minimum refresh rate is set too low.
The 120Hz refresh rate doesn’t seem to make a lot of sense if frames can’t even transition at a rate that keeps up with it.
The main use is for VRR, with bigger ranges making it more usable (and input latency should improve, but few games are going to run at 120fps). However, it seems like the feature is mostly broken in retail games, with it only really working in that paid tie-in game.
The original impetus to do these comparisons was that there were reports of significant motion blur on the Switch 2, so comparing it was the whole point.
And indeed, it’s even worse than the original LCD Switch display.
Yes, although the approach that was fixed only applies to Hyprland and some other wlroots compositors. You can use the virtual edid approach on other systems, but it may not be supported on Nvidia GPUs. You can also use it as a simple supersampling method, such as rendering at 1600p to a Steam Deck, for example.