But that is part of the game, not a thing you are adding in top of it. Even in something like the white box, if my memory is correct, it talks about making dungeons for example.
But what is the point of all this hairsplitting? I just don't even understand where you are trying to go with this. Everyone understands one of the things that makes table top gaming unique is there is this sense of possibility when you sit down at the table, and that the experience feels so different from other media (like books, video games, etc). No one is saying table top games are not unique. I think we are just puzzled by the fixation on this point (so much so that posters who are usually at odds with one another, appear to be on the same page scratching their heads here).