Back when Klingbeil was in business, Don Klingbeil (or maybe it was a Klingbeil factory rep - this was a long time ago) told me that on a well fit full custom boot (i.e., the size and shape of the boot are designed for the foot, including the position, size, and shape of the outsole), the outsole would correctly show the correct mounting position for the blades. Presumably, not because the outsole determines proper position of the blade, but because if it is fit right, the outsole will be sized, shaped, and positioned correctly.
Unfortunately, not everyone gets well fit full custom boots. If you don't have that, there is no reason your outsole should determine proper mounting position.
Think about it: if you use stock boots, or only slightly customized boots, you probably chose the length and width of your boots as something of a compromise, because your feet didn't exactly match the boot shapes.
BTW, not everyone agrees with that. And in fact, if you offset your blade too much to the left or right, then, depending on how your boot is constructed, it may warp or twist the boot in an undesirable way. I suppose that in extreme cases offsetting it too far forwards or back could do the same thing.
Mike Cunningham, who was a quite well regarded skate tech, once told me that if he mounted the blades much too far forwards or back, other skate techs would claim he had done it wrong, so he would hesitate to do go to extremes.
But for the most part, many of us have decided that small changes in position from those that are nominal are OK, if they work better with our bodies. And some of us think that even the length of the blade should have as much to do with your foot anatomy (projected vertically, because most boots enforce a forwards tilt and bend of your feet) as with boot size and shape.
But of course, you can make your own decisions on such things. I think people shouldn't be afraid to experiment to determine what works best for them.