The kind of postpartum mother-baby separation that makes pacifiers helpful should not be allowed to occur in the first place. And with careful attention to positioning, latch-on, and how well the baby is sucking, nipple soreness can be kept to a minimum, or even avoided completely. This comfort sucking is different from the active, vigorous suck a baby uses to bring down the milk that will satisfy hunger. At this point, some mothers may choose to use a pacifier. However, breastfed babies can do their comfort sucking right at the breast, because the mother's milk flow slows to a trickle as the baby's sucking becomes less intense.
Babies can continue sucking without stuffing themselves and without swallowing a lot of air.
Bottles and artificial nipples don't have this infant-controlled regulatory system. The milk flows at a steady rate, and a baby with a full tummy who wants to suck for another ten minutes may end up overfed, with gas bubbles and spitting up soon to follow. Here's where a pacifier can fill an important need. Pacifiers sometimes serve useful purposes in breastfed babies, too. They can calm a baby whose mother is unable to nurse at the moment, because she's driving, paying for groceries, or caring for an older child.