The problem is that people keep consuming the samey low quality content instead of skipping it (think superhero movies and Netflix series that are all indistinguishable from each other). As long as they're satisfied with that, they'll fall for fake product reviews too.

Someone did something like that to identify HN authors (as in correlating similar writing styles between pseudonyms) a few years back, for example: https://news.ycombinator.com/item?id=33755016

Or a study applying similar analysis to LLMs: https://arxiv.org/pdf/2308.07305

Of course, LLM output can be tweaked to evade these, just like humans can alter their writing style or handwriting to better evade detection. But it's one approach.