Except the Windows world shows it isn't a technical hurdle either. Microsoft makes their OS, OEMs buy copies of it, and stuff bloatware and crap and change stuf

Except the Windows world shows it isn't a technical hurdle either. Microsoft makes their OS, OEMs buy copies of it, and stuff bloatware and crap and change stuff all the same as Android vendors before selling it to consumers. But then, despite modifications, Microsoft updates their stuff, including the kernel. It doesn't actually even take hardware vendors being ethical and making open source mainline kernel drivers for their parts. They could just be shipping DKMS kernel modules instead of baking their trash into fixed kernel releases. But they simply do not, because they don't care.