It depends how much you talk to your pet I suppose. I mean, addressing them by their name - fine because the pet (well dog) will understand that. Certain words are commands for dog so there is also that.
When you do baby voice to your dog? Well not so crazy I think (and yes I do it). But dogs notice a persons tone of voice. While it doesn't know what you're saying exactly, it knows that you're not mad at them for whatever reason and enjoys that.
As for talking to pets that have no chance of understanding anything you say? I think those people are mad anyway to choose lesser pets.