Several years ago I looked at a Mk6 Gti - it was up for sale in used car garage, a branch of a big a big dealer group punting on trade-in's. As they have the VW dealership as part of the group - they had access to the history of the 3 door, tornado Red, one owner low mileage Mk6, but in the history, it had under VW warranty a new engine installed 20k miles ago and and then later entire new intake at great expense.
So - it may be a wasteful dealer thing where they just replace the whole lot as a unit rather than drilling down into individual components.