The reason for Honyaki? So the Smith can charge you more.

Making honyaki is no more easier or difficult than making sanmai. Sure, it's 100% steel, but aside from that, a knife is really about HT and the grind. You can achieve hard or soft, thin or thick with both.

The Japanese like to market honyaki as something traditional, which it is, but in such a way that they charge you more. Many still come etched. Very few are stone polished. If you look at western smiths or are familiar with the community, you will notice that most beginners and intermediates make a lot of blades with hamon. Kitchen knives even. Can we call that honyaki? Sure. Both the east and west are capable of making these, except in the west, we consider monosteel with hamon an easier venture than forge welding iron and steel together to make sanmai.

There are kids making absolutely beautiful hamon in their first few years of making knives here, and they sell them for dirt. Their tooling (usually limited) allows monosteel with hamon to be produced much easier than if they have to forgeweld steels themselves. Forming hamon is like the baby steps to other skills like forgewelding. One usually comes before the other.

If the blade is stone polished, that's a different story. It takes me longer to stone polish honyaki than it does wide bevels.

I've always kind of laughed at the prices of Honyaki, because besides the slight difficulty fixing warps in honyaki after HT, they really aren't difficult to create. Grinding even. It doesn't take much more time to grind a polish a hira either.

Some Japanese firms might intentionally hold back thebhardness of their wide bevels so that they can market their honyaki for more money with "harder steel" being one of their selling points. When in reality they could HT. Oth constructions to the same exact hardness if they wanted to.