Actually vegans would argue that most herbivores (like cows and goats) do eat their own placentas after birth. Eating the placenta is supposed to give the mother hormones that help her uterus contract.
Sorry if I have made anyone on this thread throw up, but you deserve it if you clicked on this thread title!
Perhaps eating the placenta does benefit the mother but modern day placenta eaters make a ritual out of it (like a welcoming home ceremony). What do the extended friends and families get from eating the placenta of this woman?
If it is cooked in a lasagna, does it still benefit them?
This is the reality as described on websites and shown on HBO documentaries.