Oh, that could very well be the "secret new SEO sauce". I could well imagine Google having an entire division focused on the quest of dealing with backlink spam

Oh, that could very well be the "secret new SEO sauce". I could well imagine Google having an entire division focused on the quest of dealing with backlink spam SEO that is targeting OG pagerank, perpetually kept occupied by SEOs that don't know better, while a new generation of SEOs simply avoids that battlefield and aims directly at ranking inputs beyond pagerank. Thousands of artificial Chrome instances, or maybe just hundreds of Chrome extensions running on millions of instances engaging in a DSEO attack each individually well below the background noise floor. If that browser feedback is easy enough to fake then the visit pretender SEO wouldn't even need to poison an extension, they could just run it from any site they can get to run some JS on.