A .docx is a zip archive
Rename one to .zip and open it and you will find a folder of XML files. One of them, docProps/core.xml, holds the author, the last person to save it, the title and the revision count. Another, app.xml, holds the company name and the total number of minutes the document has been open for editing.
Total editing time is more revealing than it looks
A proposal that claims weeks of work and reports eleven minutes of editing time tells a story. So does a contract where the editing time is enormous, which suggests it was heavily negotiated internally before you saw it. Neither is something anyone intends to disclose.
Tracked changes are content, not metadata
Insertions and deletions are stored in the document body with the name of whoever made them and when. Deleted text is still there and still readable. Turning off the display of tracked changes hides them from view without removing them, which is how internal negotiating positions end up in the hands of the other side.
Comments too
Reviewer comments live in their own part of the archive. They survive being collapsed in the interface. Cleaning here removes the comment parts, accepts insertions and rejects deletions, which is the same result as accepting all changes in Word — only without needing Word.