The OP isn't alone. Many on here have a "money flush" when they buy a new car and immediately change out the factory fill. It's no difference.
Lot's of money flushing on BITOG...."just because".
The smart owner of a new vehicle always does a low mile oil change to remove assembly contaminants. It's not a "just because" reason.
I for sure have no proof on how well flushes work other than my motors running much smoother afterwords and subsequent oil changes draining clean.
For me it was worth the 10 bucks. I change my oil every 3,000-5,000 miles with Mobil1 or any other cheap synthetic available. My 4.3 liter motor is pushing 135,000 miles. I got the truck at 58,000 miles and have been really good on the oil changes.
My last truck was sold with 302,000 miles. Again 3,000-5,000 oil changes and a few oil flushes during the life of the motor. I know it's time to use a flush when my dipstick is dark at oil change time. From my experience the dipstick should remain clear between oil changes.