Books have some advantages. The total immersion in the subject or story of the book is quite unlike most superficial treatments that you find on the internet. Your investment of time or money in acquiring the text tends to sharpen your focus on the material. And distractions are more easily avoided with printed material in hand.
But the hands-down winner of the serendipity contest has got to be the internet in my opinion. My childhood encyclopedia happened to be Funk&Wagnels, and I, too, fondly remember skipping from one fascinating subject to another in an almost whimsical way. Isn't that now called googling? Books tend to keep you focused on a particular subject, while the internet encourages an expansion of perception. Insight is the ability to forge diverse ideas into a new concept.
Lam, if you only give your debaters credit for a half-hour of research time, wouldn't you rather they get a superficial coverage, rather than spend that half-hour driving to the library and only be exposed to the wisdom of their own imagination? And if your moss grower had published his findings on the internet, maybe it wouldn't have taken the infections researcher so many years to have discovered that info (long after his death).