This is what you said:
"willingness to put down breeding failures"
Perhaps it was misinterpreted by me and some others, but it looked like you were advocating euthanasia for foals that might just not have a perfect gait or make a perfect halter horse.
As far as breeding, it would be stupid to breed a bunch of random mares thinking that you were going to make a profit. On the other hand, many families choose to breed their own family horse just for the sake of getting a good saddle horse. In this case, they plan to keep the foal. Why should anybody moralize on them for this?
There are many unwanted horses. If they were trained to ride, chances are, people would want them. Bad behavior is most likely the reason that so many horses are rejected. Bad behavior is the direct result of poor training or a lack of training. To breed animals and not provide them with the training that they need to be good citizens is wrong.