In fact, yes, that is exactly how reviews should work, if there wasn't so many fake reviews that it's not helping. People have a tendency to review and especially comment on a review, if they have an issue with something. Even a product with 3 stars could actually be a 4.5 star overall.

The comments are more important than the number. Like with most 'metrics'. They can make you look but you really have to take a qualitative look after that. Take lots of Amazon reviews that are 1 star and if you read the review comment it says something along the lines of "Product came damaged in the box and Amazon support wouldn't replace it". Or 5 star reviews with text like "Arrived super fast, haven't had a chance to try it yet". The reviews are meant to be for the product not Amazon's service or shipping speed.

Likewise if someone buys say a fish knife and then comments with a 1 star review of "Useless, can't make proper feather sticks or split wood at the camp site." And then I may give a 5 star w/ comment "Awesome fish knife, cut up and filleted the fish I caught beautifully. Been using it for a year now and shows no signs of wear."