A baby is such a helpless little being. She may be hungry but can't find her own food, may feel dirty but can't bathe herself, may feel lonely but can't get out of the cot herself and go out to play. To some extend, the baby seems to be under the adults' control. If the adult doesn't feed her, she will never get satisfied and will just remain hungry. She's so helpless, all she can do about the situation is cry.
On the other hand...
I can't sleep when she's awake. I can't go out and play when she's demanding to be latched. I'm in so much pain when she latches, yet I can't just say, "Hey, mummy's in pain... so you settle this meal yourself k? Mummy needs some rest."
She wails in the middle of the night and I gotta wake up, no matter how tired I am. I feed her on demand and attend to her every single need, only satusfying my own needs and getting a short short rest when she sleeps. So, who's under whose control now?