You are wrong.
a) Not everybody buying an app is rating and reviewing it. Look at Angry Birds for instance.
b) Is the number of copies bought, not the price what makes it top.
c) If Apple is manipulating the reviews. Why FCPX is not four stars?
I think at the beginning people bought the app just to see and to try it, but now, people buy FCPX knowing what to expect (unless they are fool since there is a lot of info on the web about it).
Leo Hans
Editor AVID – Final Cut Pro
https://www.leohans.com