OK lets gets this sorted once and for all (if only!)
If you have more than one dog watch them together carefully. You will see in some instances one may appear to be more "dominant" than others. For example one dog may always jump out of the car before the other one. This is not dominance this is just eager behaviour and probably a badly trained dog!
At other times the so called dominant behaviour will swop and the other dog may hump the first dog (even if bitches) this is not dominant behaviour just excitement.
However if you watch them carefully you will see that their behaviour will change to each other in different circumstances so dogs certainly do not see it as dominance.
I agree that dogs need boundaries. Absolutely spot on . However these are not achieved by punishing the dog or being dominant over the dog. These boundaries can be explained to the dog in language they understand and in a way that benefits them - if that happens then the behaviour will be repeated.
An example is toilet training - old method hit puppy on the nose with a newspaper if he wees indoors. Pup learns "do a wee get hit on nose", so waits until the owner is out of the way or goes to wee out of sight behind the sofa or in another room. Gets hit on nose again and is more confused more worried and hides under the wardrobe and wees again.
Positive training method - dog is taken to place where it can wee - it wees and is given a treat, a game and has a happy owner. Wees indoors no reaction. Wees outside gets a treat and has a happy owner will continue to wee outside where a positive association is made.
A mother dog will move a puppy by the scruff of its neck but given the option of no hands and no clicker she hasn't got a lot of choice. We however have the choice to study how dogs do communicate and more importantly how they learn and can use methods that are proven, safe, easy and quick. Why use any others!
Positive training does not mean letting a dog do what it wants, quite the opposite it means showing a dog the correct behaviour and rewards it so the behaviour is repeated. The more positive behaviours a dog learns the less likely they are to give unacceptable behaviours - they have been taught how to behaviour in situations.
All level of dog sport agility, HTM, obedience has shown that Positive training is the way forward. Dogs are getting more skilled as the owners are realising what they can achieve with positive training. Look at all the HTM dogs there are now none of that could be achieved without positive dog training.
Some of my dogs can skip with me with a skipping rope how could that be achieved with dominant dog training - took a few minutes with a clicker and a bit of hotdog 
Positive training all the way.