His method assumes an "average room" for a listening window, and I'd say the dipole speakers I've heard aren't meant for any rooms people put them in, or most genres besides a solo vocalist and maybe an accompanist.
I would be curious how they would measure in a room purpose made for them though. Maybe flush mounted in a wall, extremely tall, and tilted towards the listener, with plenty EQ and open baffle woofers near each channel crossed over around 200-300hz, and a dentists bite stick and chin rest to be sure I'm in the right listening position.
My hypothesis is that being out of the sweet spot is so bad that the dramatic change once you're in it feels euphoric, and once you hear something without lots of distortion and dynamics that can be handled that it's such a relief that people love it.
Bad hunch! You'd get an insane rise in the bass if you did that, because a dipole is designed to compensate for the 6 dB/octave dipole rolloff in the bass:
This is John Atkinson's up-close measurement of the 3.6R, which shows the woofer's output without the dipole cancellation. Needless to say, it doesn't measure or sound like that in the far field. For an interesting discussion of this by Siegfried Linkwitz:
https://www.stereophile.com/content/magnepan-magneplanar-mg36r-loudspeaker-more-comments
In any case, you're overlooking the main advantage of dipole bass, without which a sealed woofer would make much more sense -- namely, its suppression of the X and Y axial room modes. To achieve similarly smooth bass response with sealed woofers you have to use four subwoofers, which would rather overwhelm the cost of a $600 speaker even if you could get your spouse to agree!
Re the room, they'll work fine in a room of appropriate size -- an LRS will not work in a ballroom, and a large planar panel in a small room will sound, in the words of Magnepan's Wendell Diller, like a trumpet in a phone booth. Wendell has also pointed out that an LRS in a large room turns into a midrange, and that it goes to pieces if you drive it too hard. Without a sub, this is not a rock speaker! It's for those who want realistic reproduction of acoustical instruments, or who put a sub on it.
"His method assumes an 'average room' for a listening window, and I'd say the dipole speakers I've heard aren't meant for any rooms people put them in, or most genres besides a solo vocalist and maybe an accompanist."
As several of us have pointed out, his method assumes point source monopoles. I doesn't work for line source dipoles, one of the reasons being that the point at which a dipole starts to roll off at 6 dB/octave in the bass depends on effective baffle size, and the floor reflection alone makes the baffle twice as large. Given knowledge of the baffle size, a bit of math would make the results useful. Well, more than a bit, actually, because you'd have to account not just for floor and ceiling proximity but for sidewalls and acoustic coupling between the baffles, and for the way the resonant sections are allocated within the woofer.
Otherwise, it seems you've listened to some tiny dipoles. My Tympani IVA's have flat response below 30 Hz and cruise at 115 dB SPL. Like the other true ribbon Maggies, they have almost perfect dispersion out to 20 kHz -- something a speaker with conventional drivers can't match owing to the diameter of the tweeter.
People with small Maggies generally put subs on them. If you want to maintain the smooth response of dipole bass with a sub, the GR Research H-frame dynamic dipole subs are by all accounts amazing.