All kids play dolls. Parents give dolls their baby girl because this is how kids would have a grasp of something about toys. Of course, it is a model for kids and babies and a comfort for them. It is like an imitation of human that they think they can play with. This is why kids talk to dolls just as they see that humans talk.
By the way, dolls were just created to give joy and curiosity to children. If they cry, babysitters would give them dolls in order to calm them down and so that they can play with them. If Baby sitters have to do something, they give them dolls that comforts them. Dolls are not only for baby girls but also for adults. Dolls can be a comfort when sleeping. Some needs needs something to hug when sleeping and some just regard it as a sleeping partner. This means that a person does not want to be alone.
You can talk to dolls also when you have no companion and you can regard them as your friends. All people must have someone to talk to in times of troubles and distress and this is the time to make sure that they are making every effort to overcome them by bursting to dolls. Thus, dolls can help to lighten the burden that we carry. Since we need warmth and comfort, we buy dolls that pleases us. Even if dolls can comfort us, if we are not pleased with it, then dolls can be meaningless.