Apparently the catchy little phrase, Adopt, Don't Shop is very troubling to puppy peddlers. I have no idea why, unless they themselves know that it's the right thing to do and hate to be reminded of that fact.
A lot of dog breeders do not seem to actually like dogs very much. The dogs are simply a means to something else -- self-identity, a slightly-elevated bit of social status, a little of pin money.
What are we to make of people who say if they could not breed XYZ breed, they would not have any dog at all? Really? There is no dog at the pound you would ever have? This speaks, to me, of a mental disorder. You see, there is nothing all that distinct or special about any one breed of dog. Breeds fall into broad temperament types, and yes they do come with different genetic codes inside them. But no breed has a n absolutely unique genetic code, and personality types are all over the map within a breed. And, of course, there's a pretty broad spectrum of pure breed dogs in rescue, same as there are plenty of solid crosses where the personality or genetic code has not been watered down at all.
None of this means that people who want a purpose-produced dog, or even a particular breed with a particular coat pattern should not look for and get what they want. But if you would not have any dog if you could not have breed XYZ, then check yourself. It is not a dog you want -- it's an identity.