But to rule the country you need half of the votes, and no matter how many parties a country has, alliances form between them as to present themselves to the population as a viable alternative to the parties currently in power. People who dislike the current government do not want to throw their vote away on parties outside those two main alternatives - changing the alliance in power takes precedence.
We have 7 political parties represented in our parliament("riksdag"), but in effect you can only choose between two alliances who each has joint policies. Which have now become about the same by the process described in the article. So the choice we have is between the guys who want to lower the tax by 1-2%, or the ones who want to raise the tax by 1-2%. The rest of the difference is rhetoric.
In Italy (but not just Italy), there are very real philosophical differences between the parties in the coalitions. On one side you still have real, unrepentant communists, on the other side, you have Alessandra Mussolini active in politics.
What often occurs is that the big center left/right party has, say, 45%, and needs a minor party (that polled, say, 6%) to push them over 50%. The minor party then gets to hold the bigger party hostage: we want this, this, and this or else there is no deal. This gives the minor party a share of power all out of proportion to their actual percentage of the vote.
We have 7 political parties represented in our parliament("riksdag"), but in effect you can only choose between two alliances who each has joint policies. Which have now become about the same by the process described in the article. So the choice we have is between the guys who want to lower the tax by 1-2%, or the ones who want to raise the tax by 1-2%. The rest of the difference is rhetoric.