Well it's not that I don't understand the basic premise as you describe it, not understanding the mechanics involved would be a more accurate way of putting it. I know dice are involved and a GM and others who follow various maps and doodads.
I hope you didn't take my comment as meaning, I cannot understand why people would play these? Because I certainly didn't mean that.
Don't worry, there are more systems out there than most people could really properly know.
Dice are there to make it an experience that is less predictable than a pre-written script. I could go into my own elaborate thoughts but it's to add risk, challenge and uncertainty into the abilities of the fictional characters.