Your original question is invalid because the questioner would never ask it if they only used E-Prime. Let's re-phrase your question with E-Prime: "Describe E-Prime to me, I've never heard of it."
You get the idea now? The very form of the question affects your understanding of the answer. Through the description you receive, you begin to understand what E-Prime means to those that came up with it. In E-Prime, you literally can't state what it is to anyone else because that would go against E-Prime's rules.
The questioner cannot use E-Prime because he doesn't know what E-Prime is. And before being interested in its description, he'll probably want to know what it is (is it a law? is it a game? is it a style guide? a brain training exercise? is it a dog?).
See, "E-Prime" is a proper noun, and proper nouns don't have a meaning; they instead refer to specific things (giving them an identity). The same way Spain is a country, E-Prime is "a variant of English."
You get the idea now? The very form of the question affects your understanding of the answer. Through the description you receive, you begin to understand what E-Prime means to those that came up with it. In E-Prime, you literally can't state what it is to anyone else because that would go against E-Prime's rules.