Well-known critics are valuable for two reasons, even if they have wildly different likes and preferences from me: 1. they have seen/heard a lot. A professiona

Well-known critics are valuable for two reasons, even if they have wildly different likes and preferences from me: 1. they have seen/heard a lot. A professional movie critic watches more films in a month than I have in years. That gives him opportunities to compare, or to draw connections that I cannot. 2. they are known quantities. We have a certain image of Roger Ebert (as an example) in our minds and can adjust his reviews to get closer to our hypothetical opinion about the film. Also, we get to know his mannerisms and idiosyncracies. Nothing makes Roger Ebert a priori a better reviewer than Mike from 4chan who obsessively watches films, but having a handful of critics we recognize is more valuable w.r.t. these two points than having thousands of unknown reviewers.