Yes, PageRank makes assumptions about what good content is and furthermore those assumptions are probably inaccurate in a lot of cases (dishonest clickbait can

Yes, PageRank makes assumptions about what good content is and furthermore those assumptions are probably inaccurate in a lot of cases (dishonest clickbait can have a lot of backlinks). But it is unbiased in a sense that using human raters following guidelines is not. Moving from a purely algorithmic approach is a step away from being a neutral delivery service towards being a publisher, which carries extra responsibilities if you have as much power as Google.