I think you are referring to this
The only reason they say do not reset the CBS on an oil change that is taken before your actual interval is so they can track when you actually "need" it based off your mileage vs. when you changed it. At least as far as I can tell that is the reason. There are other items that are based off the engine oil service, such as the recommendation that spark plugs be replaced at 45k miles or every third oil change.
"Oil change is determined from the engine oil condition sensor which monitors the oil condition, oil level, and oil temperature, and from additional algorithms using these parameters: engine load, fuel consumption, time and distance since the last oil change."