Breast milk, while an irreplaceable wonder drug for a woman's child, carries some of the same disease transmission risks as blood does. I'm a maternity nurse and we have to label breast milk before it leaves the patient's room or it *must* be discarded, due to the risk of it being given to the wrong baby or even the right baby after it's considered "expired." This is a big risk with the neonatal ICU babies since they stay with us a while. It carries antibodies, which are great, but also viruses. It's got about 1 million active immune cells per teaspoon in mature milk (7 million in colostrum) but there's always a chance that a viral particle can escape. Milk banks have crazy tight biosecurity to prevent this.
If we could engineer a product that protected babies from acute illness, diabetes, asthma, and obesity like breast milk does, it would sell for more than platinum. Unfortunately, the real thing does come with a small but serious disease risk for unrelated folks.