Nvidia literally refuted this argument and come out and say they don't force devs to leave out FSR. DLSS workshop also includes tools for devs to put FSR and XeSS in their games along with DLSS.

Where as AMD responded with PR bullshit and fuckall.

https://www.tweaktown.com/news/92002/amd-sponsored-games-with-fsr-dont-feature-nvidia-dlss-support-and-thats-little-strange/index.html