“Ever heard of” deletes the phrase “have you” entirely, making it, in its own essence, a slang-style contraction, which is not “proper English”. That’s why I don’t care nearly as much about what is “proper English” as much as what makes sense, or what works well in a technical setting.
Do you know why I said it? I said it because you said "ever heard of emphasis" so to be sarcastic I almost copied you, just replacing emphasis with "proper English."
