There are reasons why it is called the WinTel alliance. Fortunately Linux dominate the server market now, hopefully this will give AMD some breathing space.
Don't forget that AMD can submit changes directly to the Linux Kernel but has to request or help Microsoft to make changes to Windows.
https://www.anandtech.com/show/5448/the-bulldozer-scheduling...
The reality is that Windows doesn't recognize the new CPU and so it's not using a scheduler optimized for it. Where as AMD could have upstreamed any necessary changes for Linux to fully support it months ago.
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-n...
It just seems that Linux avoided any regressions this year but Microsoft didn't.