That's interesting, but considering this note:
We recommend the GameInput API for all new code, regardless of the target platform, because it provides support across all Microsoft platforms (including earlier versions of Windows) and provides superior performance versus legacy APIs.
For games developed on the GDK for Xbox One, GameInput is the only input API
I'm really not sure this would do what we both want it to do. If everybody has had a GameInput version of their controller support since last-gen and we're still getting limited to the XInput feature set I don't think it sorts out gyro-on-Xinput at all. I am not familiar with the behind the scenes of how modern engine controller code is handled, but this sounds like maybe it's how games with native PS controller support are doing that, but not necessarily a new standard that will allow the default XInput PC setting of new controllers to pass gyro input to games detecting them as an XInput device. I think it's more like MS's answer to Steam Input as an additional layer between the games and the hardware, regardless of what the hardware is using.
It does show that all the tools are in place. MS has control over all the involved APIs. They could expand the Xbox controller API feature set tomorrow, whether or not they add the hardware feature to their base controller model. They just... don't. And Steam could deploy a Steam-independent Steam Input driver or software to just take over all controller support on a dedicated full-feature OS layer, but they also don't (on either Windows or Linux, as far as I can tell).
Honestly, there are enough workarounds (add games as non-Steam games, use Switch modes and so on), I just bump against the edge cases of it often because I'm both a controller and handheld nerd, so I'm stuck with a GPD Win handheld that insists on injecting their internal gyro as mouse inputs, which confuses the hell out of half the games, along with a bunch of GameSir and Gullikit controllers that do weird things with gyro, like injecting it at the firmware level instead of passing it to the OS. And I mess around with enough emulators to also end up with "oh, this was on DI mode when I booted RetroArch, so now all my buttons are in the wrong places until I quit". It's only dumb for like ten of us... but man, is it dumb.

Isn't that the idea?
I used to live in a place where they just don't do ice in soda at all, and it's like licking a can of dried out syrup. In the local Imax they didn't even have ice at all as an option. They looked at me like I was insane when I asked, then calmly pointed out that the soda comes out of the machine chilled. I just had to learn to watch two hour movies while sucking on a tub of lukewarm, full-strength soda like a deviant.