I was the obnoxious kid who kept asking "Why?" Somethings never change, and here I am still.
Actually, asking why leads to understanding. Asking why is a sign of understanding there is more to it than you might know. Which is the first step of learning. (You fix the age-old saying: '"I do not know what I do not know" .. and as such, I do not know what to ask' )
It is pretty easy for me to understand why major cutting and root pruning are each major traumas to the tree, and I can see why you don't do them close together. I don't see how wiring is also a major insult. Trees are not mini Einsteins and I don't see how bending a limb causes any physiological change to the tree. Can somebody explain?
A branch is not a solid piece. Rather, it basically a stick with many little tubes in them surrounded by a thin layer of actively multiplying cells, surrounded by another layer of tubes. If you bend a branch you put pressure on these tubes and some of them rupture, collapse etc. Just consider what would happen if you tape a bunch of straws together and then try to bend it (Or even a single straw). The thin layer of growing cells is distorted changing the configuration ever so slightly. And the outer layer of tubes may slightly move compared to the inside.
All these things are thing a plant can deal with. But it does affect the physiology of the plant.
DOes that make sense?