Well. the idea is that honing with spine on the stone wears spine and edge at the same rate hence maintaining angle. then people tape the spine so it won't wear and ...

There's a lovely maths based thread on it. Ah well.

But to refine that argument further ... The spine and the edge will not only wear at different rates (due to force being spread over a larger area at the spine: assuming a hollow ground razor, very small area at the edge. Pressure is force divided by area. speed of metal erosion is proportional to pressure not force) but also wear in different planes. The wear at the edge is into the face (the width of the blade) at a rate proportional to, but not equal to, the wear on the thickness of the blade, whereas the wear on the spine is only to the thickness of the blade ... so original geometry can never be maintained, tape or no tape.

(The maths in the thread, however, has convinced me that this is like arguing about the difference between a duck. So please don't see this as an invite to re-re-re-[etc]open the debate)
(unless you want to. it is temporarily and locally a free world, so do as you will )