There are no psychological benefits.
Forcing a newborn baby to drink testosterone isn't a benefit, in case it's not clear.
And, I realise you probably don't know this, but a mother's milk can be transferred to a bottle and used to feed a baby by as many people as they like.
A man doesn't have to take copious amounts of drugs, and squeeze an un-nourishing bit of liquid out of his nipple in order to do it.