Dogs don't feel threatened by your intelligence. You can train a dog. Dogs are easy to buy for. You are never suspicious of your dog's dreams. The worst social disease you can get from a dog is fleas.
Dogs understand what NO means.
Dogs understand if some of their friends cannot come inside. Middle-aged dogs don't feel the need to abandon you for a younger owner. Dogs admit when they're lost. Dogs are color blind. Dogs aren't threatened if you earn more than they do.