This is an excerpt by Robert E. Greene from an essay he wrote for The Absolute Sound.
For decades, it has become a fashionable matter to worry about “soundstage,” but this has reached the point that recordings are expected to have a soundstage almost independently of what the recording is—to expect the soundstage to be a property of the playback system rather than reproducing what is recorded. To my mind, this is a matter of using reflections off the walls, especially the first reflections off the sidewalls, to generate an artificial sense of space. People may like this but it is not really reproducing the recording. And the impression is very unstable in detail because it is not really there on the recording. (Some recordings actually have outside-the- speaker images because of phase effects from spaced microphones, but most recordings do not have this in any systematic way). Because of the instability, the idea has arisen that all kinds of things that really have no reason to be part of the reproduction of space at all can be evaluated according to their effect on soundstage, with enlargement being always regarded as better.
If you're truly interested in stereo microphone recording techniques.