It's incredible that people like you are bitter because others are given a choice and they don't choose what you would want them to. And all in the name of freedom, no less.
I have no bitterness here, just facts. It's important to understand that none of these WSL features has anything to do with open source. It's exactly your standard "extend" stage.
See: proprietary hypervisor runs OS with a patched non-upstreamable Linux kernel and then there is proprietary userspace drivers and libraries that able to talk to their proprietary parts inside Windows.
Can any of it be used with different hypervisor? No.
Can it be used with open source drivers? Again, nope.
If Microsoft or Nvidia wanted to use open APIs they would just support technologies that already exist, e.g there is GPU virtualization with Virgil 3D. There also VirtIO which is standard for all kind of virtualized interfaces, but again Microsoft only interested in using their proprietary tech.
Microsoft could also just use Vulkan instead of bringing proprietary Direct3D user pace to Linux. Or might be they could actually open source parts of their stack, but then it's will be against their vendor lock-in.
