It can seem cruel to crate train a dog but in reality it's not as cruel as a person would think.
Crate training your dog can give it a sense of security and keep him/her safe especially while you're away from the home and can prevent the dog from destroying your home as well if they're in a crate instead of out running around the house.
However the dog should not be left in the crate for longer than 8 hours at a time otherwise it could mess with the dogs mental health.