To me a "holy grail" wouldn't just be about being superior, but about being complete. Even within the web space, with its simplistic UIs, React doesn't do a lot (intentionally). Whether it's a shining diamond of mathematical beauty or a plug in the bunghole of the web stack doesn't matter in that regard. For a complete UI you need more, and then the bikeshedding starts.

And Desktop UI libraries tend to be even more complex. And as usual, warts are on the outside.