That's not what they meant by mess. They weren't talking about the editing from scene to scene. They were talking about the number of ships in the frame, and the varying degrees of ability to discern who was doing what and where. They thought the actual dogfight part of the dogfight was cluttered and incomprehensible.
Which is wrong.
ah ok. that makes sense. well not their reason for thinking the ROTJ dogfight was a mess. that's a bad reason.