I mean Plato thought reading books would make people more stupid.

not true. This can help you 👇

from Phaedrus, Discussion of rhetoric and writing

This final critique of writing with which the dialogue concludes seems to be one of the more interesting facets of the conversation for those who seek to interpret Plato in general; Plato, of course, comes down to us through his numerous written works, and philosophy today is concerned almost purely with the reading and writing of written texts. It seems proper to recall that Plato’s ever-present protagonist and ideal man, Socrates, fits Plato’s description of the dialectician perfectly, and never wrote a thing.

again from the Wikipedia page:

They go on to discuss what is good or bad in writing. Socrates tells a brief legend, critically commenting on the gift of writing from the Egyptian god Theuth to King Thamus, who was to disperse Theuth’s gifts to the people of Egypt. After Theuth remarks on his discovery of writing as a remedy for the memory, Thamus responds that its true effects are likely to be the opposite; it is a remedy for reminding, not remembering, he says, with the appearance but not the reality of wisdom. Future generations will hear much without being properly taught, and will appear wise but not be so, making them difficult to get along with.

No written instructions for an art can yield results clear or certain, Socrates states, but rather can only remind those that already know what writing is about. Furthermore, writings are silent; they cannot speak, answer questions, or come to their own defense.

Accordingly, the legitimate sister of this is, in fact, dialectic; it is the living, breathing discourse of one who knows, of which the written word can only be called an image. The one who knows uses the art of dialectic rather than writing:

“The dialectician chooses a proper soul and plants and sows within it discourse accompanied by knowledge—discourse capable of helping itself as well as the man who planted it, which is not barren but produces a seed from which more discourse grows in the character of others. Such discourse makes the seed forever immortal and renders the man who has it happy as any human being can be.”

☞ Phaedrus on Project Gutenberg