In the real world, it makes sense. In game terms, it doesn't. Having metal weapons ignore the hardness of other metal weapons negates the need for hardness.
This is one area where fantasy diverges from reality. In D&D, a nonmagical club made of wood in the hands of a raging barbarian can shatter a longsword.
In other words, this was a concept that they avoided in the core rules. If you want to include it, you're not following the game rules, but it certainly makes sense. It may, however, lead to some bad ramifications by making sundering too easy ...