Another point worth bringing up, and one I think Taleb (and Eco) would agree with. Those books are valuable as a storehouse of potential knowledge. Their use isn't that they have been read and stored in your head; their use is that they are there and can be drawn upon immediately and with ease when you are pursuing a thread of thought that you want to turn in to an essay.
The internet serves a similar purpose though it is not as immediate and personal as an antilibrary. In fact you can translate Taleb's proposition to the internet as well by pointing out that the pages you've read on the internet are far less valuable to a current project than the massive storehouse of knowledge that exists there that you haven't read. You could just as easily reframe it as:
The webpages you have read are far less valuable to what you're doing now than your ability to use your search bar.
Books and antilibraries aren't the internet, and I think that one thing the internet lacks is the felt sense of smallness that you describe here in your article. There's something about having the knowledge of the world hidden behind a screen the size of a small window that feels less... substantial? Less real? Less something, surely, than having your own library of books that crowd your space and remind you of the magnitude of the knowledge you have yet to get to.
But you also have to imagine also that for a scholar who existed prior to the internet, an antilibrary was of the utmost importance; it was their personalized Google. Anyone engaged in a creative or scholarly occupation that required knowledge was limited in the generative phase largely by the size and content of their library.
If I am a writer thinking of an essay on freedom in the 1600's an integral part of my writing process is likely to be perusing my shelves, looking at titles that are either directly or (I suspect) tangentially related to freedom, selecting ones that seem promising, and skimming them to see if the author has value to help me develop my ideas. The books are the raw dots in the connect-the-dots game of knowledge.
In other words, the reason that encyclopedic authors in the past were encyclopedic was because they surrounded themselves with encyclopedias - and whatever other books they could find.
