We have two ears, we have two eyes, two legs, two arms. We are creatures of stereo by design. We listen in stereo regardless of what our "audio system" produce. Reading stereo is an illusion is almost weird to me seeing we are wired in stereo.
"we are just imagining things" ?
nope
"we are experiencing things"
Sometimes (many times) in this hobby we attempt to re-write the rule books, instead of playing by them.
"is soundstage important" ?
well
"we live in a sound, visual and other senses, stage"
Fortunately we were born into a life of soundstage. More fortunate is that audio designers early on implemented stereo in playback.
All the rest is us talking about it.
Michael Green