Because they cant. DLSS only works on nvidia hardware so the developer would be forced to remove upscaling completely for some gamers if they went DLSS only.
why would that be a factor? the devs that take deals like these wouldn't give a shit either way. we have heard from studios that PC versions are just the afterthought versions that barely get attention.
DLSS would be nice and all but can we stop this hilarious narrative that nvidia is taking the altruistic approach. I'll believe it when Nvidia allows all versions of DLSS on geforce 2xxx and intel cards.
that would mean a massive performance decrease, at least on AMD. Intel cards could most likely muster it, but it would need to be adjusted specifically for it.
but on AMD cards, if you even tried running DLSS2 you would most likely have almost no performance gain, maybe even a performance decrease over native. either that, or the quality would need to take a hit, at which point it would be basically FSR2.
that's why XeSS being cross compatible basically is useless. they most likely did that so that the implementation rate is higher.
but if you use XeSS on anything but an Intel card, you will have worse performance than FSR2 and barely an image quality gain over FSR2. I am actually not sure how good XeSS on AMD cards looks compared to FSR2.
did anyone ever make a detailed comparison with that?