They don't measure how good your service is. Or how optimal your product is.
They measure how well you did compared to expectations. They measure how well people rank you in the survey.
That’s what Seth Godin says and he’s not wrong. Remember how you used to take tests that you could game if you were a good test taker? Basically those kinds of tests only tested how well you took tests, not how well you knew the material. Same difference.