It’s not really true. There are real cases where people have radical, obvious insights. Look at history of science and math!
I.e. the famous scientists were not that smart - they were just the smartest and therefore first to react to the waterline of knowledge in their domain rising high enough.
I'm not sure how common this dynamic is in science and maths. Certainly, as you learn more, your ideas and concepts are inevitably refined. (Like: no plan survives contact with the enemy). But I don't know whether that "refinement" is too subtle to count as a "pivot".
However, serendipity has a storied past in math and science.