Why is one of the lowest rated reviews on main page?

The very positive review, with only 9 out of 25 considering it "helpful" (35%), is given preference to a review with 27 out of 34 considering it helpful (79%).

In my experience with IMDB, they favor "helpful" reviews for the main page.

I could MAYBE understand if an algorithm was giving preference to higher star ratings to be nice, even though this would be deceitful and misrepresentative, but the review voted much more helpful has no star rating for an algorithm to detect.