Of course, Shirky is being glib; the internet is a great boon. (After all, he published his musings online.) Shirky is illustrating the Schumpeterian reality that widespread access to publishing on the internet has reduced the absolute value of the (now) simple act of publishing. What's left? Quality, duh. It's not enough to have your voice heard. Your voice must hold some kind of value to matter.
The Internet has been in majority use in the developed world for less than a decade, but we can already see some characteristic advantages (dramatically improved access to information, very large scale collaborations) and disadvantages (interrupt-driven thought, endless distractions.) It's tempting to try to adjudicate the relative value of the network on the way we think by deciding whether access to Wikipedia outweighs access to tentacle porn or the other way around.
Unfortunately for us, though, the intellectual fate of our historical generation is unlikely to matter much in the long haul. It is our misfortune to live through the largest increase in expressive capability in the history of the human race, a misfortune because surplus always breaks more things than scarcity. Scarcity means valuable things become more valuable, a conceptually easy change to integrate. Surplus, on the other hand, means previously valuable things stop being valuable, which freaks people out.
To make a historical analogy with the last major increase in the written word, you could earn a living in 1500 simply by knowing how to read and write. The spread of those abilities in the subsequent century had the curious property of making literacy both more essential and less professional; literacy became critical at the same time as the scribes lost their jobs.
(HT Tyler Cowan)