It's not nonsense. You are forgetting a very important detail: "explaining".
He was not talking about writing a research paper on the simplest possible terms. Rather, about "explaining" a subject. When we are explaining, we always have to deliberately omit details to get the basic idea across, so that the other person can form the initial mental image. Sometimes we also have to resort to metaphors and comparisons from entirely different fields, or relate them to real world concepts.
Once that is done, then the lengthily process can begin on improving the fit of that mental image to the subject. This will require more explanations, more focused, in a different level of detail.
Case in point: dimensions higher than three. Most people cannot conceive what the heck a tesseract is, or why it is usually drawn the way it is. But then you can tell them to watch Feymann's Flatland scenario, and they will be able to understand the basic concept.
Are they mathematicians now? Hardly. But now they have some understanding on the subject which they did not have before, even if it is on a very high level. And can try to absorb more details, if so inclined.
Er, they may be left with a warm and fuzzy feeling that they have some "understanding", but let get them to do some multidimensional analysis and see how they do. The meaning of "explaining" seems just as elusive as the "simple explanations" themselves - once you've heard such a "simple explanation" and have a feeling that you now understand more than you do, what is the objective difference between you-before and you-now? It's my experience, and several professors have confided the same, that the "simple explanations" give students a nice feeling that they "get it", up to the point where they actually try to apply the knowledge and fail miserably. Maybe the explanation then wasn't really "simple", but now we're just shifting the goalposts further into epistemology.
I would tentatively agree that there is a skill which allows you to break down complex subjects into digestible chunks, but that usually depends a lot on the student as well as the teacher(e.g. some people are good at following metaphors, others learn very well from repeated examples, etc), but the outright statement in the topic suggests that there is no such thing as irreducible complexity, which seems ludicrous.
> "Er, they may be left with a warm and fuzzy feeling that they have some "understanding", but let get them to do some multidimensional analysis and see how they do."
Nobody's having any delusions that explaining is the same as teaching. You can explain multidimensional analysis simply if you understand the subject fully, however you can't teach something to someone else unless they work with you and try it out themselves.
But if you want to explain to your politicians that hospitals need special machines to do radiation therapy you don't enroll them into nuclear physics 101, they can probably do with a very broad explanation of how radiation works.
He was not talking about writing a research paper on the simplest possible terms. Rather, about "explaining" a subject. When we are explaining, we always have to deliberately omit details to get the basic idea across, so that the other person can form the initial mental image. Sometimes we also have to resort to metaphors and comparisons from entirely different fields, or relate them to real world concepts.
Once that is done, then the lengthily process can begin on improving the fit of that mental image to the subject. This will require more explanations, more focused, in a different level of detail.
Case in point: dimensions higher than three. Most people cannot conceive what the heck a tesseract is, or why it is usually drawn the way it is. But then you can tell them to watch Feymann's Flatland scenario, and they will be able to understand the basic concept.
Are they mathematicians now? Hardly. But now they have some understanding on the subject which they did not have before, even if it is on a very high level. And can try to absorb more details, if so inclined.