This. Given the choice of dealing with a world that is always shiny, bright, cheerful, smooth, clean, and instantly responsive and a world that is frustrating, demanding, ambiguous, unyielding etc an infant (and a helluva lot of adults) will remain transfixed by the screen to the detriment of their physical and mental development.

Not every moment of it's existence, but a vast majority to be sure. Babies can't do anything for themselves. They are completely worthless and prone to self-injury and self-harm.

It doesn't have to be a single person or it's progenitors, but it does need to be someone who genuinely cares for the baby. When I was younger I remember my mother and father would often watch babies for other young mothers who needed time to relax. This seems like a good model, but our culture's irrational distrust of men invalidates half the pool of helpers and our growing disconnection from neighbors and other people jeopardizes the rest.