I think much of the controversy regarding "alpha" and "dominance" comes because of semantics and the tendency for some to oversimplify canine behavior. Most veterinary behaviorists tend to dislike the older terminology and methods - basically not believing in dominance, strict punishment and control.
Most believe that dogs have evolved enough that their social structure and patterns identify less and less with wolves and have basically their own patterns.
Essentially, the veterinary behaviorists see a more successful method (with less stress to the dog and risk to both dog and owner) using methods that don't include physical domination and punishment when the dog is not compliant.
This isn't an area of expertise for me, but I tried to summarize my understanding of what I've been hearing about from the veterinary side.