> what if each receiver is able to handle the ultrasound scattering better

Yes, that's the most charitable 'Steel-man' possibility I've still got open. Still a lot of unknowns but I suspect they're just unknown to me and probably already known to those in the field. It's not like this off-axis receivers concept is remotely new in computational imaging. So I went looking for priors and proxies that use the same idea - and found a bunch. There are dual-wand, dual-leaf and quad-leaf 'flex-jaw' arrays that basically just add extra receivers on tilting 'wings' to conform to cylindrical and non-uniform shapes. They don't seem to be used much for medical imaging but are common in things like metallurgical inspection, materials analysis, etc.

I'm still unclear why they aren't used much in medical but I suspect it has to do with the fact that medical ultrasound is highly constrained. It can work well in fat and soft-tissues but bone absorbs and reflects ultrasound fiercely and different tissue densities respond differently. This makes off-axis receivers likely to be occluded, reducing how often it contributes to improving imaging.

My biggest question about the MJ product hypothesis isn't whether it can work, it's whether it will work meaningfully better than easier, cheaper surface-contact methods using the same transducer chips. If it's true that additional off-axis receivers do provide increased value for medical imaging, then it should be even better to do that with a flexible semi-arc of chips that can directly touch the skin. I just don't see how any off-axis benefit can overcome the drastic signal degradation introduced by moving the chips 200-400 times farther way and trying to correct for the turbulent hurricane of that huge liquid volume.