PageRank is also not unbiased, it has been played before many times and pure PageRank would be pretty easy to play - that's why Google keeps tweaking it years after it was invented. And still SEO industry exists. Now, SEOs just compete on being on the first page, not claiming something as grandiose as "truth" - add that to the mix, and all the biases there are, and you get pretty much hopeless task. And of course you get under a constant stream of criticism, and maybe also government regulation - it's one thing to just produce search results (even that is controversial, remember "right to forget"?), it's another thing to claim being able to "detect falsehood" - that's very sure a way to get sued and for the government to get involved.