It's not convincing. By this reasoning, we shouldn't take any supplement and simply eat whole foods that contains the vitamins in supplements.
Eating whole foods is preferable, but there are reasons that make taking supplements practical.
In the case of synthetic ascorbic acid, it becomes the only practical source of vitamin C when intake of huge quantities is required. Eating large quantities of fruit to attain a large dose of vitamin C isn't practical. Large quantities are needed for therapeutic purposes.
It's only practical to eat fruits when it's a maintenance dosage of vitamin C that's needed.
Doesn’t make sense from an evolutionary perspective.
If getting that much vitamin C in nature in a day isn’t practical, maybe we are not meant to take that much. Maybe the RDA are wrong