See, when books were written by hand and copied by hand, they were of course more valuable. A book was likely to be handed down among generations of students and teachers, so those handwritten manuscripts were Law with a capital L. Once books were able to be printed in quantity, the idyll was that it would put that Law, that valuable education, in the hands of the masses. What was less obvious to the idealistic printer, was that all that education encouraged many of the masses to also write, and - now their books in turn could be distributed far and wide.
And - *gasp again* - these new writers might not have the same beliefs as the early manual copying brigade. Heresy! What happened, of course, was that the noise to signal ratio went up. Early handwritten MSS had to be pretty good otherwise no-one would bother to copy the entire thing out by hand. Printed books, well, anyone could suddenly throw together a book and have it achieve wide readership. Andrew Keen is now in the same boat as all those other fuddy-duddy luddites in bemoaning how everything is heading rapidly shitbasketwards.
Trouble is, of course, if we hadn't gotten a printing press, and all those books, then Albert Einstein would have probably been a brilliant farmer with a keen grasp of seasons and rainfall... If we hadn't gotten printing presses, we might still believe that the Universe revolves around the Earth.
Those printed mass produced books sparked us across an intellectual revolution in the space of maybe eight generations. The early manual manuscripts shaped the direction we began thinking in, the first printed books accelerated us along that path. And yes, there were bullshit books in among those - but we're big kids, and we can usually make up our own minds what's crap and what's not. We've done pretty good at it so far.
And when you're talking Internet publishing, yes the volume of diaries has increased astronomically, but so has meaningful content. And (aside from Andrew) we seem to be coping with that and sorting our truths from the dross.
Lastly, think about traditional book publishing cycles. You had an idea, it could take years from putting the first thoughts on paper, to someone picking up your book and reading those thoughts. Now think about blogging. You think it, write it - and I read it. Sometimes within minutes. The speed of reinforcing ideas and thoughts has jumped another whole order of magnitude, and the progress of the last 500 years will seem a snail's pace compared to what will now come out of the dialogues we are able to carry on thanks to the Internet.
Here are some else's thoughts on Commander Keen's book.