> And most of the games won't behave the same way running on AMD than on NVIDIA.

I see you must not have played a lot of games recently – granted, you will notice some problems form time to time, but they are rather the exception (and often fixed by post-launch drivers updates) than the norm.

> Also, most of the games require at least XYZ version of DirectX

Also, most of webapps require at least version XYZ of browser ABC. What is your point exactly, that developers use new features of APIs/libraries?

> that's what has major quota; using your argument

No it's not my argument. In my argument, Windows + DirectX is a standard akin to the web standards, and this standard is implemented by multiple controller makers, GPU founders, screen producers, etc.

Thankfully, I can play Il-2 or Rainbow 6 as well with my GTX1070 and ASUS than my friend with is Vega GPU & LG screen.