How can you not have multichannel system

Agree with Tvad, and with few exceptions even the audiophile press seems disinterested. I can see how a mid-line Blu-Ray or SACD mch system might get broad traction across the HT segment, but that's about it.

"If done right, sacd multichannel music will best stereo counterparts, every time, hands down."

Is it "done right" or is it "every time"? If "done right", then how? Compared to what "counterparts"? What performance level of 2ch at what cost?

The fact is that audiophiles and reviewers expend countless efforts splitting hairs/adjectives when comparing near-SOTA 2ch components. In constrast, advocates of mch offer mostly undifferentiated praise of mch systems at varying performance levels, from mass-market players and receivers on up. There seems to be very little formal vocabulary other than the "blow your socks off" variety. However, this is not to say it's impossible to assemble a great-sounding mch system.

I agree with TVAD and Mapman here. Plus I have never heard a multi-channel system that even approached a quality two way system. TAD gave up some time ago in having multi-channel systems at shows. I know why, the sound was awful. I heard their best sound yet at the RMAF-the rack mounted two ways used in two channel.

I don't think there is right way or only way to produce mch mix. As others have pointed out, most recordings are done with several microphones whether in studio or in concerts. It's then up to the recording engineer to take the raw recordings (master tapes), and mix them into N channels (where N is 2, 3, 5 or 6) that closely represents the sound at the event. Whether the resulting number of channels is two or six, the tracks are artificially created.

I've heard some recordings where the rear channels are used for ambiance and spatial information. Some other recordings place certain instruments in the rear channels. Some other recordings place chorus in the rear channels. Obviously the listeners have a preference, and prefer certain type of mixing over other types. Some might believe the real channels should be used exclusively for the ambiance and spatial informations. Some other might find "music all around" approach to be appealing. In any case the goal for mch recording is to immerse the listener into the music, and there are different ways to achieve that.

At the minimum, I found that mch recordings tend to have more robust sound stage in the fronts. That's not to say that the stereo setup is inferior for generating soundstage. It's just that with three speakers in the front it gets the job done a little easier. The speaker placements are easier, and there are larger sweet spot.

Many of the RCA Living Stereo SACD releases are a direct transfer from three channel master tapes. In such scenario, I believe the mch mix is inherently superior to the two channel "mix" created from the original three channels, as the mch content will be identical to the master tapes.

But I agree with the consensus, that mch isn't for everyone. Most people don't have the room, inclination or both.

Tvad, I think your argument is about the philosophy of recording engineers (how mch tracks should be mixed), not about the fundamentals of using more than two speakers in a mch system. Anyways, like I said earlier most people don't seem to be interested in mch system for one reason or another, and it's their prerogative.