He even emphasizes this in the piece — he extols the librarian as having the skills to recognize patterns in how people recall books, which includes imperfect memories.
I've found a great deal of use in working with other people, and they share my weaknesses far more than an LLM does. Even if I worked with exact duplicates of myself, I expect I (the one I, not the collection of clones) would still be more productive than if I worked alone- I routinely improve my own work when I read it back later after having lost context, so the context-free mes should be able to help in the same way.
It's worse than that. A hammer that shatters it's weak handle after normal use is a somewhat useful tool to the homebuilder. The hammer made out of painted cheese is only delaying construction of the house.