At a guess I suspect they mean more the route finding than the map part e.g. maybe don't send me on that nice shortcut across a mountain range if there is a blizzard up there. Part of me suspects google maps would figure this out by proxy in the same way it magically knows about traffic jams before you get to them but there are probably pathological cases where because no one is stupid enough to try it google don't have enough information to not recommend it.