But I beg the question...
EDIT: I sort of disagree with you. I'm in graduate school right now, and 90% of a modern mathematician's life is spent on keeping up with the progress of others, particularly in the last 50 years. That is true. However, over time, we also filter out the unimportant stuff. While automorphic forms may be an important field today so that we can bring in fresh minds to try to tackle the Langlands Program, once that is solved there won't be as much of an emphasis. I knew "more" calculus than Isaac Newton when I was 12 in the sense that I had learned things like Stoke's theorem that he had not even known about, but Newton's knowledge was much more of a mess, as well. The stuff you learn from textbooks is not how researchers originally discovered things. Think of the analogy of starting a fresh startup codebase that looks horrible, but becomes very polished and clean after several refactorings; it may take weeks to introduce a person to the former codebase, but for the latter it may only take a good one-hour tutorial.