Being destructive is self rewarding because it's fun. Allowing a dog to practice unwanted behavior only perpetuates it. Preventing it by using a crate keeps destructive behavior from developing in the first place. Of course, a good owner doesn't leave a dog in a crate excessively. Supervision when the dog is out of the crate to re-direct and prevent destructive behavior, give alternatives and lots of reinforcement for constructive behavior increases the odds greatly for repeating the desireable behavior. Like it was said, a crate is a tool to help when you can't supervise, but shouldn't be abused and used excessively so the dog doesn't get to do normal things that dogs like to do.
If a crate caused a dog to have bad house manners, as that poster on the other forum stated, then why are my dogs very well mannered? I used a crate when they were pups and into adult hood sometimes. They always liked their crate and went in to nap voluntarily. The crate was associated with good things and not over used. I don't use one now in the house, just because they don't need it anymore and I'm short on space. But they use it in the car and are completely comfortable in it.
So, yeah....good training is not waiting around for the dog to misbehave and then punish him. Good training is preventing unwanted behavior from being practiced and reinforced, therfore less apt to develop in the first place. And more constructive, desireable behavior being amply reinforced so it will be much more likely to be repeated in the future. If an adult dog is bored and apt to get into mischief, then a crate or safe room keeps him safe and valuables spared. Just as long as the dog is having his needs met, I don't see anything cruel in using a crate for a couple hours while he can't be supervised. I don't believe in leaving a dog in a crate all day long. That, to me isn't right.
