I'd agree with that, based on what I know. For instance, my infant daughter is on Vitamin D, at the recommendation of her doctor, because she's a pale skinned baby in a cold climate in winter and Vitamin D isn't transferred through breast milk. We call it the "no rickets drops". (Although, it's worth pointing out that pregnant women don't even need all the supplements they're taking in a pregnancy multivitamin.) But, pop culturally, I don't think the idea that vast swaths of the adult population don't really need vitamin supplementation is a "duh". In fact, lots of people seem to think the opposite.