The point is, you can read all the Wikipedia summaries you want, but they won’t give you a holistic understanding of an idea. That only happens once you have a layered, three-dimensional perspective, which writing helps you achieve.
Charlie Munger calls this the difference between “real knowledge” and “chauffeur knowledge.” He tells an apocryphal story about Max Planck, who went around the world giving the same knowledge about quantum mechanics after he won the Nobel Prize. After hearing the speech multiple times, the chauffeur asked Planck if he could give the next lecture. Planck said, “Sure.” At first, the lecture went well. But afterwards, a physics professor in the audience asked a follow-up question that stumped the chauffeur. Only Max Planck, who had the background knowledge to support the ideas in the talk, could answer it.
— Read on perell.com/essay/how-philosophers-think/