The laws in most states allow 8 weeks, some as early as 6 weeks, but these laws apply to all breeds, and for larger breeds this isn't a problem. Many breeders want to get rid of the early because they do take time and care at this time, and some breeders think the sooner they can sell them the better. The mother club of the Yorkshire Terrier the YTCA recommends that all breeders keep the pups for a
minimum of 12 weeks, tiny's should even be kept longer. Even though mother isn't nursing, she and littermates are teaching important socialization skills, such as inhibition of the biting reflex. Remember that a good breeder isn't just trying to produce an adequate dog, but trying to do what will give the dog the best chance at a healthy start. Here's a good article on why the 12 week rule is important for small breeds.
Why do Maltese puppies need to be 12 weeks old before going to a new home??