Surely the world doesn't deal in black and white. Rather issues are generally presented to us in shades of gray. With that said it's always a good exercise to imagine what an issue would look like if taken to its logical extreme.
Suppose 1 person had all available money to "invest" toward their politician of choice. All other citizens on earth are busy scraping by on minimum wage, in debt up to their ears, working for this one man who essentially gets to choose who gets elected because no one can put a single penny toward another candidate or his/her legal team to get through all the loop holes necessary to get onto the ballot, etc.
How is this a "fair" representative democracy?
Sure it's not at the point today, but one could imagine that without limits a political system's integrity can be upended through manipulation of its own structure.