I've not only 'heard' that, I've seen it! My friend had 'girl fights' in her GSD dogs that just about killed one of the dogs. She had to send one of the females back to the seller after a few months. I don't think I've ever seen anything quite so horrible. Her husband got bit when he got between them and tried to break it up. It took hundreds of stitches all over the one dog to treat her after the fight, the other dog fully intended to kill her. The same female did that to several different females she attempted to bring home.
The woman always bragged about how 'close' she was to the attacking female and bragged about how 'loyal' she was. What she took for 'loyalty' and 'closeness' was actually aggression, that she unwittingly encouraged.
When a puppy in a group of dogs starts playing around energetically and making noise, the 'top dog' will come over and hold the pup down by the neck. The human needs to be the 'top dog'. The human decides who gets disciplined, and who gets pushed away, not the other dog. When a dog takes over the 'top dog' role from the human, it needs to be told in no uncertain terms that that is NOT ON. Don't just say 'Nein'. Put the dog on a down stay and put some drama in it. MAKE SURE it knows that deciding who gets pushed away is NOT ITS JOB, or it will escalate. These things are not 'phases'. They are trying out behavior of the lead dog. It is a challenge to your position, not 'loyalty' or 'closeness'. Put an end to it in no uncertain terms.
We had a very soft dog, a mutt, who watched with great interest as I came over to the couch, stood there a moment and said to my hubby, could I lay down where he was. He very kindly got up and I laid down on the couch where he had been. After that, EVERY time I walked over to the couch, the dog would quietly get off the couch and let me sit down, but if hubby tried to sit down, he'd straighten out his legs and slowly push hubby off the couch, and not budge an inch! He would never, ever listen to my hubby. Evidently he figured he and my hubby were on the same level, LOL.