There are grandmothers that do this (I can think of one GN member) and have done through the millennia no doubt. But the point is that it is done out of need - if mother ill or dead, or failing to lactate, or if there was a multiple birth perhaps, then for most of history, unless a relative steps in, then the baby would die. So it is not unnatural in the grand scheme of things.
This however just smacks of celeb culture - trying to get lots of attention fluff.
Our Welfare State. Is it broken?