The reason they said this is because Deej answered a mumbled question in a not so direct answer because he was texting his wife. He was asked if there was only one exploreable location per planet (but the question was mumbled and tapered off) and he answered after a long pause, "Yes. we are calling them destinations." He didn't say there was only one zone per planet directly but the community took it as this and many believe that. I personally just thought he meant four planets, moon, mars, earth, and Venus. So here is my reasoning that there is more then one zone. In the IGN mars map tour video, it was said each PvP map was derived from a single player art style and there is a map from the twilight gap which is an area outside the last city according to the lore. So why would they not have a single player zone for a PvP map when they said that is where they get the inspiration from. Also from the very first ViDoc pathway out of darkness or something like thy, you can see more areas of a Forrest and tower that are 100% not Old Russia. I thing Bungie is just hiding stuff like usual, I mean why would they make concept art for old chicago, Mumbai, etc if it wasn't in the game. Guess we will find out 9/9