No, Blumlein relies just as much on time difference. The point is that both ears hear both loudspeakers. If you do the sums (it's vector addition, so be careful!), you find that a difference in intensity only between the channels translates into a difference in phase (time) as the sound arrives at the ears.
Spaced techniques get this wrong when played on loudspeakers, though despite that they can manage pretty good imaging - the brain is really quite forgiving.
In fact, the situation is much more complicated than that, as in addition, speed of propogation of different frequencies in air is different, so the time/phase domain varies every moment, depending on a frequency content.
On the other hand, if we come from a different prospective, a "normal" distance between ears (~17cm) is quite small, compared to distance between loudspeakers, so seemingly, the distance between spaced mics should be whether 1) negligable in regards to the distance between speakers, or 2) that would be enough to change the distance between speakers by 17cm to get the same effect

.
Of course it does not work so.
Stereo is a psycho-acoustical phenomenon and in fact, is BASED on "brain forgivenness", or "selectiveness".
I never saw more or less convincing scientific explanation of advantages of either spaced or coincidal techniques... rather opinions.
Don't take me wrong, I constantly use MS (which is essentially coincident XY if the center is cardioid and Blumlein if the center is fig8) along with baffled stereo and ORTF, and have nothing against either... except when certain recording conditions are the limits.
Dummy-head techniques do work better than a simple ORTF head-spaced pair but they are after all only a more sophisticated version of ORTF.
As I wrote earlier, they have completely different principal. Indeed, the dummy head works well only on cans.
If I had a webspace I'd upload a few recs I made with different techniques, including ORTF, as well as Jecklin disk, and Blumlein.
Omni speakers - and indeed fig-8 - have a look at www.linkwitzlab.com He's got some very convincing arguments, and practical implementations too.
I am very familiar with Mr. Linkwitz work and very often use his website as a reference. Indeed, he is a very smart coockie.
I would not however call his Pluto or Orion omni and fig-8 respectively.
The Pluto is based on a free mount Aura driver. Because of the physical size (2") it is RATHER directional on top end.
The 2" half wavelength translates into appr. 3.4KHz, so it becomes directional already @ about 2.7-3KHz, i.e. at the frequencies which still carry a LOT of information, as far as directionality is concerned.
IIRC, the Orion's crossover point is about 1.4K. The Millenium tweeter is a closed chamber one. Considering a large baffle area it is effectively "cardioid" on top end.
Although I disagree with his design choices, I understand very well why he went or was forced to go that way, esp. considering commercial nature of those systems.
A few years ago for a customer I designed and built a 'dream', 'price no object' system from ground up, including DA converter, tube pre, passive LC crossover, and tri-amp tube cathode follower amps.
The speakers were "true" fig-8, where on top I used doubled Oskar Heil air motion transformers, for midrange pair of Audax PR170MOs, and for woofers a pair of 12" Dayton Titanics, mounted on open baffle.
The realism, imaging, transparency, etc. were breathtaking, with such bass quality and extention that it is going straight into your guts.
The only problem was... everything sounds good on that system, even recordings with a poor stereo image. It seems the fig-8 pattern with its backwave reflections, and large listening area somehow added those qualities of hall sound and localization of the source.
But wouldn't we call it cheating, getting back to where we started?

Best, M