To your point, I have heard only one setup EVER that did the 3-d soundstage to the extent you describe...and I have heard 100’s over the years I would estimate.
As I have alluded to on occasion in past threads here, that was a demo of an all mbl system with mbl 111a speakers set up at then United Home Audio in Annapolis Junction, MD, in a showroom optimally constructed for the purpose unlike anyone is likely to have at home, probably over 10 years ago.
Same system at shows, less optimally setup...back with the pack.
So I have seen what it takes and factor that into what I do at home to the extent needed for me to be happy in lieu of setting up a custom room like that and going full omni. Something I greatly appreciated but do not need to get my endless hours of enjoyment from my music at home. THis ain’t the Olympics and I have no preconception about being the best in the world. Too much trouble! But never should be too much trouble to at least learn from the best and apply what you learn as you may. :^)
My system(s): Sound Chaser | Virtual Listening Room (audiogon.com)