Dogs respond very well to strict rules! The life they get as domesticated animals is lavish (bar abusive owners) compared to how they would live in the wild, alpha males and dogs challenging will grab and sometimes tear the excess neck skin and also hind legs just to show dominance and this can go on for hours on occasions, this is a form of posturing, the real fighting can cause a lot more damage. Alpha females can be more vicious than males.
A dog isn’t like a cat, it isn’t a pet in the classics sense. It’s a responsibility, they have the ability to really harm humans in certain circumstances, you as its owner have a responsibility to make sure that your dog is disciplined and trained to a degree that means they are safe for the general public, this starts at home and means basic rule setting and boundaries for your dog, many dogs already have a good mentality around people, but some large breed dogs can be very territorial and aggressive and protective. And to train them right, and make them completely obedient and not a risk to people and children around them this can mean discipline that includes pain. Just like when you smack your child (maybe not all of you) when they do something wrong, they will associate doing something wrong with getting punished. Its not enough pain to cause any damage, but enough to deter them from making the same mistake too many times. Most dogs are very intelligent and figure out right from wrong very quickly, some dogs you must take a slightly more aggressive approach to there training.
Anyone who knows a dog breeder knows that they will tell you the discipline makes the dog. The end result is a best friend.