I'd just like to note that, pretty much the only reason I don't spend too much time in "The Books" is because I often have a headache, and trying to discuss intelligently is just beyond me.
Really, I think that it has mostly to do with just how much time and energy people have, and often they don't have quite enough to participate in "The Books," particularly when, as
Saucepan Man has pointed out about his posts, the posts are often very very long.
And there's also just so much to do on the 'Downs! If people find themselves bored just staring at it, they really should join a RPG or something...
