Let the sun shine in: Is vitamin D supplementation in breastfed babies necessary?

It is often recommended at a child’s 2-month well check (or even before) that parents supplement their breastfed babies with vitamin D due to the lower-than-recommended amount of that vitamin in human milk. According to the CDC:
While breastfeeding is the recommended method of infant feeding and provides infants with necessary nutrients and immune factors, breast [...]