I'd be guessing this is a more evolutionary capability thing than 100% necessary. There would have been numerous times in our history when an exhausted mother giving birth would have not had the strength or assistance to pick up her baby, at which point the baby's instinct to get to the breast for the sake of its own survival would have been vital.

I guess I see it as something a baby is capable of doing, but like you FJ, don't see that it's necessary for it to occur to establish a good bfing relationship. More a survival instinct than anything else.