If you believe that spondees and pyrhhic feet (which are quantitative ideas) are valid in English (which is a stress-accent language), then you would have a point.  The thing about English is that there is relative accent between any two or among any three syllables, so that the distinction between the abstract pattern of iambic stress (the stress differential between pairs of syllables) and normal phrasal speech rhythms across a phrase or line, creates interesting tensions among various possible spoken emphases--this is what Stephen and I have been referring to.  Bibliography on request, though I try to summarize the principles and debate in the first chapter of my 1985 book, _Natural Emphasis_.  If there is new information, though, I'm always willing to learn.