There can be a million things wrong with user testing, and while I am certain they know more about it than me, I think it's a safe bet to say they're not perfect either and may make mistakes in such a complex topic.
(Small example of what I mean: many people like the new style because it's prettier, but when I use OSM I get to places a lot faster than people using Google Maps, so they might be asking the wrong question even if they did user testing with a million people. But that's just one example of everything that could go wrong.)
(Small example of what I mean: many people like the new style because it's prettier, but when I use OSM I get to places a lot faster than people using Google Maps, so they might be asking the wrong question even if they did user testing with a million people. But that's just one example of everything that could go wrong.)