This is an interesting discussion, but it seems a bit polarized in the sense that (as usual) two-channel stereo or mono are both somehow considered "true" or "pure", even if other words are used. There are problems with both.
Early stereo experiments at Bell Labs in the 1930s concluded that acceptable stereophonic recording and reproduction required at least 3 channels, and that two was inadequate. (The word "stereo" does not mean "two".) They also concluded that ideal stereophonic recording required a matrix of hundreds (or thousands) of microphones, recording channels, and reproducing speakers in corresponding locations. We got two-channel stereo for practical reasons only, not because we have two ears. 3-channel stereo records would have been a problem not easy to solve.
Two channel stereo has some very important and significant flaws. One is, the "phantom center" image is quite fragile, and is easily blurred, made non-palpable, or vanish entirely by many factors, mostly acoustic. In an ideal room with two speakers, the phantom center image only works in listening positions along a line perpendicular to the line between the two speakers, and centered between them. Moving even slightly off that line causes the center image to collect closer to the closer speaker.
But, even with a mono signal driving two speakers and a perfect seating position in a perfect acoustic environment, there's a big problem. The sound from both speakers arrives at both ears, but not exactly at the same time. The difference in timing creates a comb filter effect that alters the frequency response at both ears, with the maximum effect occurring with a mono signal. Not a small dip either, -3dB to -10dB at just below 2kHz. (see "Sound Reproduction - Loudspeakers And Rooms" by Floyd Toole, section 9.1.3)
A center channel, or a single mono speaker, solves both problems. A mono speaker only cannot adequately represent the acoustic space the recording was made, nor handle more than a few point source signals very well, hence the need for L and R. Since reproducing an acoustic space (real or imaginary) isn't done well with 3 speakers, you need to add at least Ls and Rs. Then there's height...you see where this is going? It really gets down to, "If you want a sound there, you have to put a speaker there", because phantom images are just that, never really solid, and never in the same place for everyone.
You can argue that mono is better, and for original mono recordings played on a single mono speaker, you'd have a good argument over two stereo speakers trying to do that job. But neither two channel stereo, nor mono, can present a believable acoustic space without demanding quite a bit of the listeners imagination.