First past the post is synonymous with government

In a two-party system there can be an inclination to vote for one of the leading parties in the hope of making sure the opposite party is kept from power. In a sense (because power is derived from government) we are using the democratic process to 'punish' the opposition party since for them to be in power is an affront to us. But we might conclude that neither of the main parties are innocent and so then we feel disinclined to vote for either of them. We do not want to punish either of the main parties because both are equally guilty. The first-past-the-post system makes it very easy for whichever of the leading (large) parties gains the most votes to form a government (since its popularity is magnified). With a proportional system the winning parties seldom gain enough seats to form a government on their own... they must negotiate a coalition proving that government itself is unnatural... particularly by one party. Government by coalition is not much different from anarchy and is not government in the same sense as government by one party or one leader. Government in a winner-takes-all system such a mayoral election is very different than by proportional representation because once the election is over (under pr) there is still plenty of negotiation to take place.

For true government (without a coalition) we require first-past-the post. First-past-the-post is synonymous with government in a way that pr is not.