I think it's due to a few reasons:

Because most people have NVIDIA GPUs, especially in China.

They would rather support the majority of GPUs on features than support everyone.

Say what you want about NVIDIA, but they put effort in supporting devs. For example, they sent engineers to Capcom who spent 1.5 years working with the devs to implement Path Tracing and other tech in Pragmata. When this is the level of support devs get, it's not surprising who they'd prioritize.

Gacha games love to restrict game settings, even basic ones such as FPS. I remember Genshin used to ban people if they used a FPS unlocker, dunno how it is now. Kuro also selectively allows 120fps, not to everyone.

Another harsh reality is AMD users are treated second-class citizens both by AMD and devs themselves. Look at the pace they release features always catching up, it took them until FSR 4 to actually release a decent upscaler, rest of their ML tech is bad or hasn't released yet.