Except that there may be other things as well missing in the vegan diet that have not yet been identified that cause problems for babies. It's like baby formula -- they keep "improving" it because they keep identifying new things in human milk that they realize they need to add to baby formula. Babies need breast milk from a mother who eats a balanced diet and a balanced diet for human beings includes animal products.

Interestingly, human milk (at least the milk of humans who eat a diet that includes animal products) is very high in fat and cholesterol and I saw some studies several years ago that showed that children who were nursed by their mothers are less likely to have cholesterol problems in adulthood. (They do have high cholesterol in toddlerhood, but it goes down as they reach adulthood.) The exposure to fat and cholesterol early on may protect them in some way. One of the reasons for the explosion in high cholesterol and heart disease in the past century may be the decrease in the percentage of babies who were breastfed for most of their infancy.