Yeah, I agree that they are living creatures and thus there will be some uncertainty there. But often the "logic" (I quote that because I'm skeptical that it's actually logical) is that when one buys from a breeder, there is risk that the dog will not turn out to meet the buyer's needs, while on the other hand, a buyer could rescue a dog which they are more able to interact with the dog to see if it meets their needs or not.
I'm making the claim that if the breeder is consistently producing dogs that have a structure that you prefer, whose breeding stock holds a temperament that you prefer, whose dogs are producing wins in the sports you prefer, whose dogs are maintaining a modicum of health that you desire-- then such "gambles" are so far reduced to be almost negligible. But rescue, you generally don't know the baggage, or the health, or the background, or really anything that you get when buying from a quality breeder.
I just don't see the logic in stating that a rescue removes the gamble that a puppy brings.
C-ATCH Pimg - DOB: 2/06, RATO, UJJ (x2), DJX, HIT, CA, CGC, High in Games, Reserve High in Standard- CPE Nationals 2014
RATCHX2 High Jinks vom Neuanfang - DOB 9/12 (Gotchya Day: 1/23/2013) DN, CA