True learning is understanding. True understanding is linking new information to existing knowledge and applying it to problems.
Book: How to Take Smart Notes
We have to take notes in our own words because that forces us to elaborate new information with existing knowledge (vocabulary). Zettelkasten Method further forces us to incorporate new things with our cognitive structure.
This also relates to Meaningful Learning Theory, which adds the importance of applying. "Meaningful learning occurs when the learner interprets, relates, and incorporates new information with existing knowledge and applies the new information to solve novel problems."