Immersive.... it is a specific type of illusion.
In fact strictly speaking the original meaning of stereo is, "providing a solid/3d impression" - and in its early 20th century initial use it was aimed at a 3 channel setup.
Well recorded 2 channel stereo - played back through a well set up 2,3, or more channel system can indeed be immersive, and provide the illusion intended.
Many (most) multichannel setups actually mess up the "stereo" and as a result corrupt the solidity/immersiveness of that image...
A well set up an properly tweaked 3 channel system using PLII or Logic7 (or similar) can in fact provide an excellent "stereo" image, which maintains its "solidity" through a wide listening area.... a 2 channel setup can do the same, without the PLII or Logic7, but can only do it in a limited sweet spot.
Really multichannel, although being able in theory, to be used to create "stereo" illusions, is more usually used to generate surrealist or impressionist images and effects.... it is extremely rare for an artist today to try to use multichannel to recreate a realist even.
So for those of us seeking that realist reproduction of an acoustic event - 2 channel stereo - and the means of reproducing it, remains the ultimate.
Having said all that, a well set up multichannel system can absolutely be used for 2 channel stereo.