The Linux kernel was and is a monstrosity.
And it is irrelevant anyway, given that this comment was written from 10.0.26100.
You’re saying they improved the design. I know they added user-privilege device driver support for USB (etc).; did they revert the display compromise/mess as well?
Hence why graphics usually no longer crash Windows, after a small black screen pause, everything continues as usual.
https://learn.microsoft.com/en-us/windows-hardware/drivers/d...
I don't think they ever intended to keep all drivers strictly userland, though. Just the service side.
The Windows NT code was engineered to be portable across many different architectures--not just X86--so it has a hardware abstraction layer. The kernel only ever communicated to the device-driver implementation through this abstraction layer; so the kernel code itself was isolated.
That doesn't mean the device drivers were running in user-land privilege, but it does mean that the kernel code is quite stable and easy to reason about.
When Microsoft decided to compromise on this design, I remember senior engineers--when I first started my career--being abuzz about it for Windows NT 4.0 (or apparently earlier?).