Some dogs are trained to use a crate like a "den" so they can be easily kept out of trouble when the family isn't home. My maltese is crate trained, and it actually serves as a "safe space" for the dog, especially with smaller dogs. You have to do it right - leaving the door open (the doggo is free to go where they want), never punishing the dog inside or with the crate, etc. My dog actually loves it, especially at night, and he has a separate bed outside the crate if he wants to sleep there. But he usually prefers a crate with a towel partly over the top as a sort of den.