I ran across this quote on the internet from Lloyd Brackett, famous for creating the Long-Worth German Shepherds in the 1950s. (Thanks Tim Hackworth)
"In the dog game those who criticize the system of line breeding far outnumber its proponents. This is true for several reasons. There is a continual influx of beginners in breeding dogs, people who have never before mated one animal to another, or made any study of the subject. In their ignorance they believe that mating two dogs with "pedigrees", especially if both are winners, or better yet, "Champions", is all there is to it.
Then, there are a multitude of breeders who refuse to take the time to make any study of genetics, who want only to breed dogs to sell and make money, and these have no interest in breed improvement through years of planned effort. Again, we have the many hit-or-miss breeders who hope for the good luck which sometimes strikes novices who by sheer accident come up with a real "topper" or two. In listing the opponents of closed-up (line) breeding, one should not fail to mention owners of stud dogs, hungry for stud fees.
Fortunately there are in almost all breeds of dogs a very few fanciers intent upon consistently producing dogs superior to the average of the breed. Many of these know that the quickest and most certain way to do this is by line breeding."