It is a good point, but with time comes change. Plato was an excellent scribe of Socrates and Aristotle after him. Just because Socrates thought it was inhuman to write things down, doesn’t mean his successors did and we are all thankful they did such a diligent job in doing so. But then again the argument of writing things down expands the metaphysics of philosophy, especially Socrates perspective given it’s not in his head.
The linked essay literally claims that, even if times change, humans need to write to generate good ideas. That's why it seemed fair game to mention societies with different norms and different training.
