Sorry if this is a dumb question or one that is asked a lot.

Why use washers on the outside of the scales when peening? Why not just make the hole slightly 'V' shaped so the pin spreads into it and holds the scales tightly--like in pocket knives? (Particularly, the liner-less variants).

Is it just aesthetics or are there other more practical reasons?

I do have a practical reason for asking, in the blade I am restoring, I kind of...er, demolished...the original washers. So I was just considering options.