Scholars who study writing differentiate between knowledge telling and knowledge transforming.

Highlighting can be seen as a weak form of knowledge telling. It's a low level indicator that an idea is important, but doesn't even go so far as the reader strengthening the concept by restating the idea in their own words similar to the Feynman technique.

One could go steps further by not only restating it but transforming it and linking it into one's larger body of knowledge or extending into other contexts.