Little to no monetary benefit, hardware changes now need to be documented for Linux, loudest and most critical users but smallest volume.
I don't know if that's true. Linux users are curious and will try more stuff but people mistake that they file bug reports (and usually detailed ones...) with complaining more.
Apple's MO is that it's their baby. End of. They don't do open. Their compiler is closed source, and so on.
And risk of loss of control on the software ecosystem.