[pjmlp]

For the same reason Sony, Nintendo and Microsoft are, they care about specific parts of Khronos, not all of it, not for all their products.

Sony cares about Khronos on Android phones, not so much on Playstation.

Nintendo supports OpenGL 4.6 and Vulkan on the Switch, with NVN as the main API. During the previous generations they started to support GL like APIs, not really 1:1 to the standards.

Microsoft was the main contributor to the initial set of GlTF 2.0 improvements, and BabylonJS is the first browser engine to driver most of the WebGPU efforts, and they care about Khronos APIs in the context of WSL.

Apple once cared about Quickdraw 3D, OpenGL was the path out of the tiny market they were in and what NeXTSTEP used anyway, nowadays all relevant game engines support Metal anyway.