I think it's a matter of filters. On Twitter where there is almost no filter, you will be reading almost exclusively garbage. You may just be better off reading erotic romance novels than reading unfiltered Twitter. HN is a little more tightly filtered, the quality of stuff posted is generally higher, and it's probably more worth your time.
But it's hard to beat hundreds or thousands of years of filtering through the best thoughts of the best minds. When you pick up the plays of Sophocles or the writings of Cicero you know that people from radically different societies and ages of history have found wisdom and insight in their thoughts. So I think there is some "magic" in books in that they have had time to age, and that thousands of very smart people have found value there.