I would go so far as to say that knowing and understanding something is only half of the issue. The other half is being able to clearly convey it to others. And that’s where a lot of people (myself included) fall short.
I think any scientist should able to convey at least the high level concepts that they’re working on at the level that a smart 12th-grader can follow. If you can’t do that, I think that’s a sign that you’re probably not thinking about your work very clearly. Being able to distill things and context-switch back to a birds-eye view of your work is critical for knowing what direction you’re heading in.
(I say this from the perspective of a climate scientist - our field has a pretty active public/lay conversation and lots of science comma, but I think the concept still applies to other sciences, and social sciences.)
