The birth of article spinners and relevant technologies in the internet marketing industry has come forth precisely because of this position in the "great debate." Most people are terrified that even though Google does not still hold the capacity of detecting when you've published an article to one place or another, that they will eventually be able to do so, and when that day arrives, the concern is, and the thinking goes that the search engine giant will greatly discount the weight of any back links embedded in, or appended to (by resource box) your copied article.
By extension then, if an important part of your online income derives from keywords you have obtained solid ranking for using the same tired handful of articles, posted out to actually hundreds of different places, then on the time that Google makes this dreaded improvement, your earnings will decline in the best case, and in the worst, Big G will see you as a spammer, and basically de-index most or all of your sites.
That, at the root, is the greatest concern behind this particular position in the great duplicate content debate, and it can have certain compelling features to its argument. Given that Google always plays things so close to the vest, and has long history of closing loopholes and getting it significantly hard to "game the system," the thinking is, at least on a certain level, sound, because it can easily be argued that this IS a classic case of gaming the system (especially in light of article directory submission program that can definitely give you a push-button method to send a single article to a thousand or even more directories for publication).
The most apparent and commonly cited defense, then, is by using OTHER technologies, like article spinners which, to varying degrees (and mostly dependent on the skill of the an individual using the spinner) generates semi-unique versions of the article in question that (it is hoped) will make the articles more tasty to Google. Of course, the visible counter is that this too, is a sort of gaming the system. It merely takes the game to the next level, but be that as it may, the current thinking of those who fear duplicate content in the world of internet marketing (therefore, the relative popularity of spinners) is that its days are numbered, and also article spinners are the solution to getting and keeping yourself right with Google in the long run.