Exactly. Not too long after my wife bought her Dodge Durango she started to complain that sometimes while driving the engine would rev really hight but not go faster and then all of sudden she felt a lurch/thud. Then my sister in-law said it did the same to her. When I drove I never experienced it and could never get it to do it. So I took it to the dealer to check it out. They could not find anything either.
Then I realized that she was probably accidentally hitting the paddle shifters on the steering wheel. Sure enough that is what it was, she would accidentally downshift with her foot on the gas and of course if revved high and then when it would shift gears back up there would be a slight jerk because the high rpm and shifting. Now she watches to make sure she doesn't touch the paddle shifters and no more issues. Since we took it in to check out that would probably be considered a "mechanical problem" per the survey but it wasn't.
That's not how the JD Power IQS study works.
They only assess real problems (i.e. nothing to do with the user not being able to figure out something). They don't assess subjective problems or fake problems.
The whole aim of this study is to look at things as objectively as possible. Yes, it does include a survey, however it would be careful not to take any fake anecdotal reports as real problems.