This feels to me like a slightly tweaked form of an "appeal to novelty". The most insightful people alive today are not automatically more insightful than everyone who has died. Just because we are alive now doesn't discount the importance of previous works (and this is ignoring that today's society is based on our ancestors' philosophy and views).
Not to mention modern stories are often based on older stories, and those who write modern stories by definition were informed by older stories.
Those stories that "anyone could have told" went through the ages through these specific people, in this specific form.
When you have knowledge of history, of old texts, your self is equipped to be free from manipulation of those that pretend that "things weren't this or that way, but my way" for their own benefit, because you know, because you have something material that holds together, that went through the trial of time, that says otherwise.
The modern counterparts, for instance, pick hugely on old stories, old arcs, and old myths.
But you only get that when you care to read and appreciate old stuff.
We have our own culture now, we spend far too much time worrying about what the dead did with their limited free time.
The books in the western canon are important because they are good and went on to influence everything you consume today, even the narrative in super mario. Take some time to read a good chunk of these books and you will be wiser than most people you know on all sorts of topics.