Hidden from view is not removed
Word's markup display is a viewing preference. Setting it to show the final version hides the revisions from you and from nobody else. The insertions, the deletions, the names and the timestamps all remain in the document body and are visible the moment anyone changes their own view setting.
What this reports
How many insertions and how many deletions are recorded, and the names of everyone credited with making them. That last part matters: a document can carry the names of people at your organisation who the recipient was never meant to know about.
Accepting is the fix
Accepting all changes resolves the revisions into ordinary text and removes the record. Cleaning here does the same thing directly on the file, which is useful when you do not have Word to hand.