You will have to trust when I say the last time I tested this (not when I wrote the comment) using the data scheme without a doctype tag still disabled quirk mode. Clearly you are very knowledgeable about the browser so I am willing to concede defeat here. :)

edit: I suppose what I'm trying to say is: I wouldn't hold it against an engineer with proven experience if they don't know what quirk mode is, but I would become suspicious of their capabilities if they couldn't imagine any justifications for it after giving them a quick rundown of what it is and how it works.