I still remember when it was the norm for features like this to be entirely implemented in the EC and behaved sanely in any OS, even one that doesn't know about ACPI. For example, on old Thinkpads you can adjust the screen brightness, audio volume, and turn on/off the keyboard backlight in DOS. No drivers needed at all. The outliers were the stupid designs that would overheat and shut down if you left the laptop sitting in the BIOS setup screen for too long, because the fans would stay off. Several decades later, ECs have gotten much bigger flash and RAM, and BIOSes have bloated several times, yet modern laptops need an OS and a massively complex driver loaded just to do something trivial. I recently discovered on a new Thinkpad that the screen brightness was not adjustable in the bootloader, or even early in the OS boot, and that GPU drivers were necessary for that function. A regression which by any other name would just be by design. IMHO this is the increasing fragility leading to the closing of the PC ecosystem that MS ultimately wants.