As the saying goes here in the States, "I was wrong once ,but that was when I thought I was wrong!" LOL!I can be just as wrong as the next man
But once shown to be wrong I am right from there on in till that theory is proven wrong
Comes from a scientific educational background
There are no absolute truths just the best descriptions that the current technology will allow.
As for the original poster it is confusing for them but as no one who posted actually knew the spindle assembly then it is a case of common sense and sound engineering practice .