In my opinion, if it sends the baby off to sleep, then there is a possibility that the noise remains and becomes a habit, so that eventually it may become addictive, in the same way that sleeping pills for adults do.
If parents use one and find the baby cannot sleep without it, then addiction to white or any other noise has already set in.
If a baby needs a noise to go to sleep, why not the mother's heartbeat or speaking? I know we are human and not animals, but we could take a leaf out of their book when it comes to newborns. As soon as the calf, kitten or puppy is born it communicates with the mother's voice, so that the baby knows it's own mother in a herd, because, like human babies, the foetus knows the mother's voice and recognises it.
We don't sleep with our babies, but that doesn't make it normal, and being left alone may lead to insecurity. Why a white or any other noise, rather than the mother's own, recorded helps I don't know.
If the brain sorts out experiences of the day while we sleep, it puts them into perspective, and all is saved in the brain cells in that part of the brain responsible for whatever experience. That means the sound of the voices around the baby are stored forever and memory is created. No one knows if the recordings of white noise take anything away from the baby and replaces it with meaningless noise, because the jury is still out on that one, but instinct tells me not to do that.
I may be wrong. I am not infallible. It is just my opinion. Viva la difference!
If a quiet life for the parents is more important than the memories stored in their infant's brain, then they have a right to that peace and quiet, and who am I to deny it? I wouldn't, but then I loved to read the bedtime stories to my children. They were reading and writing before they started in kindergarten at 4.