For what it's worth, I do not believe that this is Apple's strategy. Squabbles with Khronos suffice to explain everything.
It's not so clear-cut, they're pouring a lot of resources into WebGPU and Safari.
This, they literally posted a TON of engineering WebGPU jobs just recently for their WebKit team.
This is true, there is so much more that Safari could be capable of if it gave developers lower level hardware capabilities, but that would hurt the bottom line…