While this statistic is astounding, the more important and significant factor is the trajectory. As the yearly percentage of PB dog ownership rises, so does the percentage of PB kills (and one would presume non-lethal but disabling mutilations of humans, with it).
This gives the lie to the propaganda-biased article.
IMHO, unwanted PB-type dogs winding up in ASPCA care or yhat of dog shelters should be immediately thanatized with prejudice, as a sane measure of preventing cruelty to humans.
This is a gray area. I assume you meant "euthanized" and not "thanostized".
It really depends if the history of the dog and its previous owners are known. If it was treated well with respect and loved by an owner who died; I think there's no reason that dog can't be adopted out. Hopefully to someone who knows how to handle that particular breed.
If the dog's history is unknown I would agree a good professional dog handler would need to assess the dogs individually over time to determine if they can be saved. A difficult call.
Some dogs, regardless of breed, must be put down for the good of all; including the dog. If it was abused or neglected to the point of turning it into a feral beast, well, sadly many times the dog can not be rehabilitated.
To just kill them all willy nilly like you stated just proves your ignorance on the subject. Go back to reading your little statistics.
I doubt you're familiar with Husky's or Akita's. These are other breeds that must be handled differently than your run of the mill Labradoodle or whatever. Rotties and Dobies too. PB's are not unique in needing a different handling technique than the Labradoodles. Amateur dog owners who have no clue are a bigger problem than anything else IMHO.
Your mileage may vary. For what it's worth. Just my humble opinion.