Must not have been very dominant males
I do believe dominant dogs exist. Yet dynamics are always changing. For instance, in my dogs, the old male eats when he wants, lies where he wants, moves the others, or corrects the dogs as he sees fit. Then normally the others fall sort of numbered on down. I have brought in others that challenge some, replace positions, etc. Every once in awhile a fight may break out, usually the lesser dog backs down.
Usually dogs that live together have a structure, dogs just meeting go through all sorts of positions. It's not as simple as a stance or one rolling over. One dog may display lots of dominant or submissive actions, and then there is fear, insecurity, aggression, many number of things play a part.