The idea was that people choose representatives from among themselves, wise and trustworthy men who then get together to discuss and decide on common things for the common good. But it was already in the first Finnish election that parties emerged. That put an early end to the idea of people choosing representatives. Politics is a matter of power, control and money. As was mentioned above, all too often even worse motives than those are there, directing the way things are run.
Elections are just a time of much illusion and manipulation.
And remember, a party starts in one way but transforms very quickly into something totally else. In the beginning the party perhaps even did actually represent those who helped the party to be formed, but that changes soon. People are what parties feed on. Their money and voluntary work and trust and loyality. People believe the best and close their eyes on obvious failures and character problems and more.