Quote Originally Posted by cpcohen1945 View Post
The results -- the shape of the final razor -- are exactly the same for both methods.
That's where you're wrong. The result in most cases is not the same.

Most razors do not have perfectly straight edge, but rather a curved one i.e. a smile. It matches the curve on the spine in a very specific manner because the hone is a flat plane. and you only hone one point of the edge at a time.

By breadknifing you are destroying the relationship between the lines along the spine and the edge (actually bands, the one along the edge is called bevel) that must lay on the same plane while honing and reestablishing that takes longer time and takes more steel off the razor.

Regular honing strokes modify these two bands very gradually keeping the relationship intact, so there less work to be done overall.

This is a bit mathematical, so understanding it is not everybody's cup of tea, but it is what actually happens.