Why aren't blimp drones more common?

Sorry i'm not knowledgable on the subject but isn't most energy consumed by drones is used to keep the drone in the air?So if you connect the drone to a balloon with helium that keeps the drone in the air and just use the motors to control direction wouldn't you be consuming a lot less power and you could keep flying for a longer period of time?Sorry if this is a stupid question, thanks for reading. via /r/drones http://bit.ly/2ZCwxAo