Some breeds have so much energy and are so active that if you do not give them a sufficient workout every day - a long walk and hard run - their pent up energy will quite likely manifest itself in destructive behavior.
All dogs should get as much exercise as possible. A daily walk is sufficient for most breeds. But most small dog breeds, for example Toy dogs such as Pugs, Maltese or Yorkshire Terriers, will get the majority of their required exercise needs just be walking, running and playing around indoors.
Most all dogs will get along well with children if they are raised with them. However, some breeds have a protective streak in them and may become aggressive with children who get to close at meal time (although this should not be tolerated), or aggressive with children they have never met. These breeds will likely see the children as being underneath themselves in the "pack order" and may try to dominate them.
No one is suggesting that people should not get a dog from a shelter or rescue if that’s what they want to do. Many breed clubs were among the first dog rescue groups in the U.S. Breeders love dogs and believe in rescue. But people should also have the option to purchase a purebred dog from a dedicated breeder without harassment or guilt. And breeders should be able to breed their dogs without punitive laws.