Bjørn, I cannot agree with your first paragraph. Things in nature are there, even if only for a moment. For the rest, I think you are not distinguishing what is there from how we perceive or interpret what is there. Depth of field is only a matter of perception, and black and white is an artistic representation of what is there. Nature does not have edges, but human perception does.
This is very different from the issue of putting in important elements which were not there in the first place. Take, for example, the first picture in the National Geo series. If the two men were really there on the edge of the tall building, then Wow! If they were not, well, congratulations to the skill of the pp creator, but zero marks for producing a worthwhile nature photograph. Same for others in that series, including the man diving into the stream, the diver with the shark, the large herd of rhino and the kids with the monkey.