Can I have the source for this? DX12 dropped exclujsive FS? Why does every game still has this as a option then? Or are you talking about VR specifically?
Games may show it as an option if the engine itself can support other GPU APIs and the devs working on the options menu don't know or care that this particular settings combination is misleading.
[1]: https://learn.microsoft.com/en-us/windows/win32/direct3d12/s...