It may well be a myth, which is why I said 'if anything'.
You choose to explain away this myth in a very plausible way, explaining the distance between the various parts of the brain and doubting that there could be any link between them. Yet, in audio we are expected to accept many myths, despite similarly convincing argument and evidence to the contrary. I'm afraid you cannot have it both ways!
Touché!
I don't doubt there's a link between these sections, I question it. I am open to the suggestion that there may be a link, but currently such a link is outside our scientific purview. But new developments in neuroimaging happen all the time.
Interestingly, we used to think the cognitive pathways of speech and music were identical, until someone noticed that we have pitch-sensitive neurons in an entirely different part of the brain. The idea had been posited because our reaction to music is so different to our reaction to speech, but there was just too much convincing evidence to the contrary.
As for speaker designers not recognising their own designs, again it simply shows that their design is not sufficiently distinctive within the test group.
The situation you describe should only occur where other speakers offer a similar performance or have similar character.
Another explanation is that perhaps their speaker isn't doing quite what they believe and expect. It is very easy to spend time designing something and becoming convinced in the process that what you are achieving is unique, or doing something exceptionally well. In a group, and up against peer products that might not be the case.
Lastly, if a speaker truly is very 'different' and the designer cannot identify this, I'm afraid I'd have to conclude that the designer doesn't understand what he has created, or is deaf to what he has created. Stress and pressures from blind testing come way down the list of probable reasons.
I don't hold to the idea that blind tests are stressors. Those who sit on blind tests usually do so regularly enough to eliminate any potential stressful nature permeating the test results. Nevertheless, it still seems odd that someone who knows the curves of their own loudspeaker better than they know the curves of their own wife should fail to recognise those curves in a line-up. Especially if they can also recognise the 'signature' of another designer consistently.