Population size is a big problem. The more you scale up a democratic system, the more it becomes difficult to bootstrap and maintain a coherent political movement that can have a realistic chance to win an election, in what is probably a logarithmic scale. So the bigger the country, the more entrenched the options will be, which eventually boils down to two sides when you approach certain thresholds (one for the current government, and one against it).

France has had a million parties. Romania, too. Italy, same. If there's a will, there's a way. Most of the time there's no will.