Comment by pjmlp

Because most game developers aren't religious about APIs, they implement an abstraction layer in their engine, a practice since the heterogeneous 8 and 16 bit days, where all major games were mostly coded in Assembly, and move on.

Any conference talk schedule at one of these conferences (https://gameconfguide.com) will prove the point of how little they care.

It is all about gameplay, taking advantage of gaming IP, franchaises, how to squeeze the ultimate performance out of specific hardware, user engagement,....

You will find an occasional talk about open APIs, probably even done by some Khronos folks, and that's it.