I hope that people understand that all of what I've said relates to work where, except under exceptional circumstances, I cannot strike someone.
I also admit, that when it comes purely to blocking, it doesn't matter where the hands are. You can use the shoulders, as Arthur pointed out, or rotate the trunk or step back, etc. So you're right, the math argument isn't a great one.
I also pointed out though, that standing with my arms to my front relaxes me. Me personally. Not necessarily anyone else.
And, my skill level as compared to an Arthur or Rob sucks, so what I do will probably involve my hands vs. his upper body anyways. Though, admitedly, with more training I could attack lower areas of the body with the lower areas of my body (though still not with strikes).