I'd agree that "immersion" is a massive target, and all of the best hifi/musical moments I can remember at home have been when that box has been ticked and I've been utterly transported, into the soundstage, into the performance, into the beauty of the sound, into the beauty of the music. That indeed seems to be a worthy contender for the biggest goal I have in any system or listening session.
I don't really know whether electronics or speakers make a larger difference in nurturing or destroying that sense of immersion, but I know the single biggest factor in my own personal experience of it is me. It's predicated so much on mood, time of day, mental state etc., that I almost don't trust it as a repeatable measure of quality. There have been too many times that I've spent an evening utterly intoxicated (no, not in that way!) in front of the speakers, only to find the spell broken when listening to the same music on the same system the following day. If I could find a system that could guarantee to put me back into that intoxicated space every time I turned it on I'd be happy indeed!