Imagine you walk into a shop to buy a drink and are told you can have either Coca Cola or Pepsi. You don't want either and point to a whole host of other drinks on the shelf.
The assistant shrugs and says you are welcome to choose any drink you want but explains you'll only get what is the most popular at the moment, so you might as well choose from the two that have a chance of winning to improve your prospects of affecting the outcome.
You walk out of the shop in disgust at such a ridiculous restriction on your choice.
Yet this is exactly how our current voting system restricts our choice of politician. No wonder voters are frustrated.
A proportional system would mean the vast majority get their choice. It introduces more competition and allows more diversity and representation. In short it is more democratic.