Many noname controller disguise themselves as x360 and the main way to get any controller working when a x360 is required is x360ce which disguises any controller as x360. You can even use your keyboard as x360. Plus this is 5 years old plus this is steam only.

It doesn't really matter if they disguise themselves as x360 or not, they are using the same tech 99% of the time.

The steam controller has it’s own dongle, with a driver in the kernel, which modern xbox controller could have.

Steam also has large incentive to put their own driver in the kernel. Why would xbox do such things? Most people use Windows.

Driver in the kernel! 99% of your hardware require no install of a driver.

Sure, yet there are plenty of devices that still require updated drivers. You still need to keep drivers updated for a lot of devices. Some devices are simple and do not need updates. That doesn't mean an interface to manage them is unneeded because the bulk of drivers don't need it. There are still plenty that do.

Just accept that because of choice and customisation not every fringe detail about your pc will be avaible in a gui unless you choose your custom solution for displaying them.

"fringe" like game controllers or video cards. Which each competing OS has in a GUI... K. Fringe I guess.