I'm almost certain that I've seen this exact phenomenon described in a sci-fi novel written before LLMs existed. I thought it was Neal Stephenson's Anathem, but a quick skim through the text didn't turn anything up. Anybody else know what I might be thinking of?
Yes it's a major plot point in Anathem. The Internet was so badly polluted with machine generated garbage that a special caste of techno priests, the Ita, evolved with the mission of doing machine augmented web searches to find valid knowledge among the vast noise.