Recent testing revealed that Arch Linux, Pop!_OS, and even Nobara Linux, which is maintained by a single developer, all outstripped Windows for the performance crown on Windows-native games. The testing was run at the high-end of quality settings, and Valve's Proton was used to run Windows games on Linux.
Causes don’t matter. Only the reality. Incompatiblies and crappy lows will keep adoption low.
Causes are a part of the reality. And when people go online and complain about how “lInUX SuXxx” because their proprietary Nvidia drivers didn’t work, and blame the OS instead of the company who is meant to be providing proper support for their devices or at least documentation for other developers to use, it plants the idea in people’s minds that the OS itself is simply inferior, which has connotations of it just being a bad system. Instead of “it will work perfectly when drivers are actually released by the manufacturer”. It tarnishes it’s reputation even after that particular device gains support, and that is another reason why adoption is low.
Hell, nVidia was actively working against having a working opensource driver reverse engineered by Nouveau. Linux is a thorn in their side and the only reason they somewhat support it today is that GPU compute works so much better on Linux.