I think you are true to a point. But great movies get almost universal praise with scores of 9/10 on IMDb or near 100% on Rotten Tomatoes.
The same goes for food; there are things that are quite controversial, but who says no to fantastic ice cream or bread?
But most importantly for movies, it is not the micro-genre that decides. People who are not into fantasy or astrology still love Lord of the Rings or Interstellar because they are particularly highly produced, where all crafts making up that movie are treated highly instead of strategizing and optimizing.
Yea but those are typically self selected sets. People that are interested in that particular type of movies watches it and rates it highly. But if you only offered that movie to the entire population, likely a large portion of the population won't want to watch it.
For example, The Shawshank Redemption has very high rating on IMDB, but also many people have never seen it and are not interested in watching it.