So here is my thinking. Please realize I do not claim to be an expert, nor have I ever done so.

With a smiling or warped razor I tend to use the edge of the hone more since it won't sit flat on a wide hone. Right?
So yes I realize that you can simply use the edge of a wider hone for this, but I have found I need to lap more often and that edge is really the only area effected. Now I have twice the amount of edges to use for this.

I admit, this is not a revelation, not everyone should go cut their hones in half. But I didn't say that either.

I like the feel of a narrow hone and the hones I have created now are just as capable as the original wider one.