Game mechanics are meant to simulate and model elements of a story to create an RPG.
A story without game mechanics can’t be an RPG. Without game mechanics of some sort, you haven’t got an RPG, though you may have an interesting narrative. So mechanics, yeah; you need them, and preferably good ones. But sometimes mechanics are over-valued, which isn’t great. In fact, an RPG that puts game mechanics before the story that the mechanics are meant to simulate begins to lose its way.