7-up or not, I have watched plenty of parents giving sugar sodas or other calorie laden drinks like sports beverages as a steady diet to young children. I can't recall any that were straight up infants like in this ad. But certainly very young children. And those children, to my eye, did appear obese. Not to mention being set on a path they will struggle to get off of, later in life.
So much modern food is terrible for you, but addictive, and advertised everywhere.