Definitely not. Parents – and grandparents – have lovingly rocked their sleeping babies since the beginning of time. Life in the womb is full motion. During the day, imagine the fast jiggling a baby experiences when a pregnant mom hustles to a meeting, or takes a hike, or goes up and down the stairs…or is in an exercise class! And, when a mom sleeps her breathing gently rocks the baby in the womb, all night long.
That’s why swinging, one of the 5 S’s, is one of the most important cues for turning on the baby’s calming reflex to help them drift into sleep.
So, when babies are born, they’ve had months of constant motion inside the womb. And, that is why it’s so unnatural for infants to sleep is a totally flat, non-moving bed for the first several months of life. By, 4-6 months, the parent can use the SNOO app to gradually wean the baby off constant motion and help the baby get ready to transition to a crib (the sound will continue all night).
P.S. Rocking to sleep is deeply a part of humanity, that even adults sleep better with slow rocking, like on a boat or in a hammock!