Prove it. One link from an authoritative source. They were never emergency brakes, they were parking brakes because when they were designed cars didn't have a park function, they were manuals and without a parking brake the car would roll on an incline unless you left it in gear and sometimes it'd move anyway. That's also why you are supposed to crab your tires, or are you going to tell be they called it lobstering your tires before they ever called it crabbing.