You like to misquote and take things out of context....lol Let's be perfectly clear. There is no pure Doodle. It has not been accepted by any major registry as a breed. At this point it is only considered a designer breed. It is not different thn a band dog. They can be good dogs. They are purebred. 

However, if we were to accept you hypothesis or lunacy Secreteriat who was the first horse in over twenty years and concisidere to be one of the best ever was bred to be racing finest. His offspring were bred to be racing finest. They should have all be great examples of racing horses since they were selected from great working stock with those proven in racing. How many of his offspring won the Triple Crown? How many won the Kentucky Derby. How many won the Preakness? Surely with the outstanding working pedigrees of working racing horses they have no choice but to produce winners of the major racing circuit fir years to come. 

Secreteriat had a successful stud career. He fetch enormous sums for his fees. However, you won't find many of that won any major stakes such as the Kentucky Derby, Peakness, or The Belmont Stakes. Some have had success, but none nearly the success of their sire or grand sire.

just because something share the same DNA does not make it the same breed. The tiger and lion share the same DNA but they are different. They have been bred together. Not for the survival of the tiger or the lion. It was not to make it healthier smh. They produced a liger( tiger mixed with a lion).it is just a mutation of each original. 

If your preference is for a mixed breed there is absolutely nothing wrong with that. Just don't lie, mispresent what it is. Don't hang papers on it and call it a purebred. Donavan admits that he was happy with the Doberman and mixed something else into it to create his new breed the Donavan Pincher. WeaponX Kennel admits that he was looking for his ideal of the perfect dog and couldn't find it. Therefore, he mixed several breeds together to produce his ideal dog. 

If I were to mislead people and add a different breed into one of my purebred dogs and call it purebred it might be considered fraud. I would be deceiving people for personal and or monetary gain. Fraudulent behavior like this has occurred and still does occur. This is part of the reasons why breeds no longer look like their ancestors. People decide to change the breed by adding something onto it in hope of producing their ideals of what they want in the breed. This is how we get rare and exotic colors in the breed. This is how we get excessive size or tinier sizes( mini, micro, pockets).