[ajvs]

Compatibility is a stepping stone to increasing the 0.8% (actual numbers) Linux population on Steam to higher numbers. If 2% or even 10% of users were Linux-based then developers would have second thoughts about choosing DirectX over Vulkan for example when it makes it more difficult for them to reach those customers.

Also the "no tux no bucks" philosophy many Linux users take in avoiding paying for non-native games.

[pjmlp]

People keep forgetting that game consoles have their own 3D APIs.

Contrary to FOSS folks, professional game studios aren't religious about APIs, as long as there is money to be made.