The article never discuss carrots, but milk for newborn/babies. It says that the first versions caused problem because they had the right macronutrient, but not the right micronutrients.
I had the same concern about a 100% diet on Soylent, so I think it makes sense. Anyway, I guess the first versions were cow milk mixed with something, so it must have some micronutrients. But cow milk is optimized for fatty acid shield, not optimized as a whole food, and mixing it may make it even worst. I'd love to see a link to the study.
Anyway, for some reason the author think that micronutrients are a failure case of reductionism, but I think it's a success case.