I gotta jump on this answer because, while it is totally in sync with the outdated approach of most historians, it is completely obsolete according to the anthropological approach. A lot of your answer relies on an outdated theory of culture known as "diffusionism," the idea that "civilization" originates in specific areas and diffuses to other areas. It was used to justify a lot of racism back in the day ("Timbuktu must have been created by white people somehow, because Africans wouldn't have been capable of building it.") I know that is not exactly what you are arguing, and I'm not calling you a racist, but the fact is that although cultures do influence each other, "civilization" is an arbitrary label and no culture holds a monopoly on invention. Western civilization would have very likely survived regardless of Roman influence for a number of reasons: The geography of Europe is very conducive to trade and centralization of trade centers, state-level societies had existed in the Mediterrean long before the Romans, and even the Greeks, and the so-called "barbarians" weren't cultureless, or "without civilization" as the history books like to portray them (No humans are, really).
Finally, although I am sympathic toward anarcho-primitivists, I believe that it is "civilization" and its way of creating large societies of people who can easily share ideas that has led to much of the most important thinking throughout history. We would not be discussing anarchy at all if we were living as uneducated feudal peasants. As a result, though I think that some aspects of American civilization, like our excessive materialism and consumption HAVE to be destroyed, or they will destroy the world, other aspects of civilization, like the ability to share ideas online as we are doing now, are vitally important to human thought and the development of ideas.