Maybe because I have a friend working on a video game as a solo developer, and putting a /lot/ of energy/money/time into art--I really see the potential in this (type of thing).
This is not really for the player's benefit to put on whatever mods they want.
This is for fast iteration for artists and creators to automate a huge (sometimes necessary evil) burden.
For that usage Nvidia's thing was way more interesting: https://blogs.nvidia.com/blog/2019/03/18/gaugan-photorealist...
That gets you usable texture assets super quickly, which is probably what your solo developer friend spends the most time on. That or models. Neither of which Stadia's style transfer helps with. They probably aren't spending much time tweaking a shader-applied post-process effect, but hey, maybe they are, and this style transfer ML thing is useful. Very, very unlikely, but maybe.
If you're building a photorealistic game. And there's already lots of tools on the market to generate these sorts of textures.
I could see this Nvidia thing used for much better looking mockups / concept art. But it doesn't seem suited for final asset generation.
Well yes, of course, and neither is Google's Style Transfer ML. These are both just prototyping tools, not a magic wand to make production-quality assets.