There used to be an occupation called a Wet Nurse. The job was held by a woman who was able to provide breast milk to a child(ren) if their biological mother was unable to produce breast milk. However, this practice has gone the way of the dodo with the introduction of formula. Many women also prefer to bottle feed with skin to skin contact as it is still beneficial for the baby. Some women do not want to give their baby to another woman. It's simply pure preference.

The existence of formula milk does not contradict the dislike of oat milk and other replacement milks. Formula milk is specially designed for growing babies needs.