While many dog owners assume that their dogs should sleep with them, on the floor or on a sofa, most veterinarians, certified trainers and behavior specialists recommend use of a high quality dog bed.
When puppies are first being house trained, a separate bed, ideally waterproof, mold proof and antibacterial should be used. Home furnishings could be damaged and risk of disease to family members is high. Most human furniture is too high for puppies and joint, muscle and ligament stress/injury could occur if young dogs are forced to jump onto and off of high places. It is stressful and sometimes difficult for dogs to adjust in later life to new sleeping arrangements. A puppy will get accustomed to sleeping with the owner in their bed, then when they get to full size, the owner often wants to change sleeping arrangements. If you know that in several years you would not want your dog in your same bed, it is best not to start.