Depends on the field of study. There are, for instance, many sites with many thousands of whitepapers each for computer algorithms, genetics, and many other subjects (I've looked into those two, otherwise I'd list more). A single site can eclipse several large libraries for that kind of information.

Or, in a more specific case, try looking for 3D rendering techniques. Info on the internet easily encompasses and eclipses all printed info on the subject, and it's significantly more up-to-date in many cases.

In a more general case though, yes, I agree that many studies would fall short if done exclusively online.