People seem to think that duplicate questions are bad and something to be avoided. I think they're a terrific asset. It helps search-ability to have the same question phrased several different ways; especially when the ultimate goal is to funnel the searchers into the discussion page with the highest quality version of the question and answer. In my mind, the issue ISN'T that the mods are holding the gates against the barbarians, it is that the culture and SO itself has not given the mods the tools to convert what the "barbarians" are contributing into a valuable resource.
But as the population increases, driveby-posting becomes the norm rather than the outlier, and large swathes of newcomers can join at once, the culture cannot be taught at a rapid enough pace to survive. It either degrades, or enforces itself by means of an iron fist.
My thinking essentially stems from eternal september. Wikipedia's early success did not require heavy moderation, but once it became the predominant wiki, it's survival, I think, neccitated it.
The details may have issues, but the overarching idea, defending the culture from the unwashed masses, might still be correct.
Its not untrue though, is it? Its really easy for such communities to really rapidly degrade.
That SO and wikipedia have both retained quality for so long, while also having strict moderators hunting a strong ideal, in areas where so many of their peers have fallen prey to the unwashed hordes, implies that it may not be so easy to discard the strategy.
It might even be necessary at such large volumes. The particulars of their activity might be maleable, but just approaching the problem (very) defensively might bot be.