Your instincts are right on. They've been specifically BRED for that purpose. They've been BRED to attack and savage other dogs.
For generations the nastier, stronger, and more aggressive males have been selected out and bred with other nastier, stronger, and more aggressive females. Only a fool or someone locked in denial would think that they've been bred to produce a cuddly, long-suffering, and submissive animal.
Did you read the whole thing?