I think I see your point here, and I find myself both agreeing and disagreeing. D/s is a complex subject, and anyone that says that submission is a progressive thing totally misses the point. But I d think that a simple model exists that will explain it, this just is not it, nor do I know what it is.
I know that right now you want to jump me about there being a simple model, but my experience has shown me that ultimately things are preetty simple. Even the most complex things in nature cn be expalined using simple terms, once we understand them. I refuse to believe that people are inherantly impossible to understand, so I beleive that we can expalin motivations once we stop looking at things the wrong way.