That's assuming reviewers only derive utility from some product's star rating and not from voicing their opinion. If it were solely game theory, we'd see tons of 1- and 5-star reviews with only one or two lines of text (as this would maximize utility while minimizing the time cost of reviewing). For websites with more affluent user bases, (Yelp, Amazon's non-video game products), that's not the case: there are some epic screeds for and against restaurants and coffee tables.
To me, it looks like a self-selection issue: people only review a product if it either (a) changes their life positively, or (b) causes them trouble. If a product only impacts someone's life in a trivial way, well, why write a 3-star review for a trivially good product?
To me, it looks like a self-selection issue: people only review a product if it either (a) changes their life positively, or (b) causes them trouble. If a product only impacts someone's life in a trivial way, well, why write a 3-star review for a trivially good product?