Google already has page score for every website out there. What makes you think that their LLM can't be made to use it? That statement sounds a lot like "AI can't generate human fingers, it will never be able to generate realistic images with humans in them" or "it can't do X so it will never be able to code Y". Shortsighted.

Google search results are much worse than they used to be. And how would an LLM extrapolate good outputs from garbage inputs?