[kemayo]

I think that the people who rate McDonald's 5-stars are probably being more helpful about the system than you are, because "restaurants" is far too broad a category to have a consistent scale within.

Instead, it's more useful to rate a given restaurant compared to its sub-genre (or at least its price band) -- was it good for a fast-food restaurant? -- so you might rate a disappointing experience at a Michelin star restaurant lower than you'd rate a clean McDonald's with fast service, just because of how they're meeting your expectations.

This results in usable review aggregates. If I look at a Yelp! listing for a McDonald's and I see it's 2-stars, I want to know that's because it's bad for a McDonald's, not just because the person rating it thinks that a McDonald's inherently has a cap of being "not great, but edible".