There's actually a method to that madness. Poodles are technically water retrievers and they don't shed like the vast majority of retrievers do. So, to keep the coats from matting, at one time they were shaved all the way down, but that caused arthritic problems with the joints. So, what we see in dog shows is called "field dress" as hair is left over the joints that need to be kept warm in cold water.
When it comes to the purebreds, there's always a method to the madness, although, I can't quite figure out what Shih Tzu wants bows in his hair. Most of the rest of the toys are shown natural. And don't let these little guys fool you. We have two toy dogs and they are the biggest meat hounds you've ever met.
I am thinking of the Standard Poodles with poofs of hair sort of formed into balls. (wish I could explain it better). Sometimes the shows will have a poodle that is shaved except for the poofy balls.
I wondered about some of the toy breeds with bows. I figured the bow kept the long hair out of the eyes and the eyes didn’t weep as much.