Samuel Johnson (1709-1784) was a prolific English author who is most known for A Dictionary of the English Language (1755). He contributed extensively to what we know about writing and literature. Recently I came across a quote of his that really struck a chord with me:
"In all pointed sentences, some degree of accuracy must be sacrificed to conciseness."
Put another way: you can be concise or you can be accurate, but rarely both.
Indeed, the need or predilection to present information that is technically accurate is one the biggest barriers to clear explanations. A reason is it such a problem is that we're trained and rewarded in many parts of our lives for the very same accuracy that makes us less understandable in other parts.
Think about it this way... You work in a university, hospital or research lab where technical accuracy is paramount. Lives or at least your reputation may depend on your ability to be very specific and technically detailed in your work. But when you go to a dinner party and someone asks about your job, you find it difficult to make it understandable. You think of abstractions or analogies, but nothing seems right because they're essentially inaccurate representations. You've been trained and rewarded your whole life to be this way. Inaccuracy doesn't seem to be an option.
If understanding is a priority, you have to be comfortable with some degree of inaccuracy. Much like Mr. Johnson said, you sometimes have to trade accuracy for understanding and that means letting go of some of the details and focusing on the big picture. It means using slightly inaccurate analogies to powerfully relate an idea. As Sigmund Freud put it:
"Analogies, it is true, decide nothing, but they can make one feel more at home."
In an explanation, the goal is to make people care, so that they'll become interested in the details and be motivated to keep learning. A little inaccuracy may have to be traded to make your audience feel more at home.