My brother had a Tiny Tears doll. Actually he had two, because I swapped mine to him for his dump truck. He gave them up when he started school, but as an adult he has been an excellent father.
My son had several baby dolls when he was little, because, after all, he was a baby and was aware of that fact. However, any Barbie that was unlucky enough to fall into his hands was immediately stripped naked and dismembered. He is perfectly normally attracted to girls these days (and motorcycles, bulldozers and four-wheelers), but also is very good with helping with the babies at church.
Since it takes both a man and a woman to create babies, and since it really, really helps if there are two parents to care for the babies they make, I think it is just fine for a very young boy to have a baby doll. After that you need to go with what he wants (within reason).
I also have known some boys who have grown up to be fashion designers – some of them did have Barbies that remained intact but that were really, really well-dressed.