I believe one of the biggest bits of proof is in fact the invisible walls...some areas are so random if you walk along paths on the sides of cliffs and go off course a bit random walls appear or countdowns to return. This could be due to 3 reasons: A) they were lazy and instead of building actual terrain obstacles from preventing us from going places they put the barriers there B) they cut off these areas from the game and put the Barriers there to stop us C)they left large areas for dlc and will open up these areas up later on