My opinion on this matter is:
I can't blame the breeders of these designer dogs. They breed because, yes
there's money to be made from people who want them. My son has one
and paid $1,000.00 for Charger who is a cavapoo. Mother a king charles
cavalier spaniel and father a mini poodle.
I don't think that this is where the problem lies. Charger will have a loving home forever, however, it's the people who buy the dogs that become the problem.
Weather a prue breed or a designer dog or just a mix from a neighbor
if the person decides the pet is not longer wanted off to the pound it
goes.
The blame for over population in the pounds in general, belongs
to the "HUMANS" who no longer have need for the free or big bucks
dog! IMO