I don't think there are many people in this industry that would disagree with this ideal definition of "commissioning completion," but there are a number of people who act as if commissioning is complete when the FPT is finished. These may be the same people who see commissioning as just another item to mark off of their project "to do" list - those who are more focused on the actions of commissioning than on the desired end result.
The outstanding action items resulting from the tests are often treated as just another set of punchlist items. This is understandable if successfully passing the FPTs is not a prerequisite for substantial completion of a project. The proper operational performance of the building systems becomes just as important (or just as unimportant) as the innumerable instances of chipped paint, dirty ceiling tiles, and imperfect drywall seams.