Noun: The purpose of private browsing is to put <insert your browser> into a temporary state where no information about the user's browsing session is stored locally. Firefox currently handles the user's privacy with a feature in preferences to clear all private data. This feature forces the user to choose between having privacy (even if only momentary), and other useful features like browsing history, and saved passwords. Users should be able to go "off the record", they shouldn't have to shoot the reporter.
Fred: I got fired!
Fred: Surfing the net.
Bob: Should have had porno modus turned on dude!