I think Feynman's quote is meant that you should not learn only the name of things and pretend to understand what they are.
There's also another anecdote written by Feynman where he describes creating his own notation for trig, or maybe calc. At some point he had to abandon it because no one else understood him. The anecdote is not as quotable, but it correlates with what you said -- it gives you the ability to talk about it with other people, so Feynman is not ignorant of this.
There's also another anecdote written by Feynman where he describes creating his own notation for trig, or maybe calc. At some point he had to abandon it because no one else understood him. The anecdote is not as quotable, but it correlates with what you said -- it gives you the ability to talk about it with other people, so Feynman is not ignorant of this.