I think Cosmik meant recorded in an anechoic chamber.
While stereo may have exploded hifi popularity. You can't say the same for multi-channel. I understand your position, and agree. But multi-channel has been met with an overwhelming "who cares" in the mainstream hifi market. It has been that way for a generation. It may grow some, but I think that will be due to VR use rather than music or hifi.
Trying to interest some of the amateur musicians I've recorded in surround recordings has proven futile. Will it matter over headphones? Will my car/suv do surround? I've got a soundbar for the TV, but its not much good for music. I don't have any way to play surround recordings. If we ever do a video we'll do that. So on and so forth. They care very much that you record them in stereo. Multi-channel even when they've heard it and liked it just doesn't gain any traction with them.
I don't disagree that Mch is a tiny niche in the traditional "hi fi" market, meaning for music listening. But, you are ignoring the "home theater" market, and my impression is that it dwarfs the hi fi market. Yes, of course the mass HT market is dominated by relatively inexpensive stereo soundbars. But, if you look at high volume electronics marketers, like Best Buy, Crutchfield, etc., you will find tons more AVRs and AVprepros dominating the shelf space or web catalog, with hardly any plain stereo gear in sight. Also, many, though not all, formerly stereo-only hi end boutiques have shifted gears and devoted much demo space to Mch home theater along with their declining investment in hi end stereo. There are countless barometers of that among dealerships in my home town area, and specialist hi fi only shops are almost non-existent.
This is not new, and it has been going on for well over a decade, more or less coincident with the rise of Bluray and universal players. Also, CES, which used to have some balance between hi end audio and video/home theater is now totally dominated by the latter. And, increasing numbers of HT buyers use their systems as multimedia systems for music too, as I do, though most probably still listen to music in stereo, unlike me. Equipment-wise, however, Mch audio will survive and continue to prosper on the coattails of HT.
There is also no secret about the fact that Mch is not well represented at all among popular music releases. Pop music production and engineering are pretty much locked into a stereo-centric paradigm, starting with multitrack recording of individual performers artfully mixed in dead studios. I foresee little change to that in the near future. Mch, like Blumlein or other techniques focused on more accurate spatial imaging, have little to no benefit for pop music as we know it.
So, yeah, Mch music is a tiny niche, largely within the small classical music niche and almost entirely ignored by the hi end audio press, except for Kal, of course. But, all that has nothing to do with reproduction quality. It is almost a miracle that the niche of Mch music even survives, but survive it does. New Mch releases keep coming from the few dozen small, mainly European labels dedicated to top quality classical music production. Mass popularity is not their objective, otherwise they would not be recording classical music at all.
Let's also not forget that we now live in a globalized, internet connected world. Specialized market niches can survive and prosper in this economic climate, unlike the difficult days when most everything had to come from local brick and mortar stores.
I don't mind being in a niche. The water is fine over here. I have collected more Mch music recordings in 10 years than I ever did on LP and CD combined in the many decades before - thousands. And, the sound is easily the best and most satisfying of my decades-long wanderings in the wilderness of audio.