Pedagogy requires empathy, to know what it's like to not know something. They'll often draw on experiences the listener is already familiar with, and then bridge the gap. This skill is orthogonal to the mastery of the subject itself, which I think is the reason most descriptions sound confusing, inadequate, and/or incomprehensible.

Often, the disseminating medium is a one-sided, like a video or a blog post, which doesn't help, either. A conversational interaction would help the expert sense why someone outside the domain find the subject confusing ("ah, I see what you mean"...), discuss common pitfalls ("you might think it's like this... but no, it's more like this...") etc.