First past the post is a monarchist system

In a democracy people should be able to vote for whomever they like and have their choice respected... but if a winner-takes-all system is in place then people must consider voting tactically. If proportional representation is not assured then it might make sense for voters to vote tactically if their fear of one of the main parties is greater than their desire to support their preferred party. If the state doesn't make sure to guarantee a proportional outcome then the voting system will suffer from the truth of Duverger's law and it is likely that a two-party system will emerge.

If there is a two-party system then one will tend to be more 'socialist' than the other simply because this is the primary axis of all political conflict. So then the party on the right will be seen as a more monarchist (and perhaps liberal) party and the party of the left will tend toward socialism and communism. If people are not monarchists and reject the ideology of monarchism they are left with only the socialist party with which to register their opposition to monarchism. Such voters might decide that they are willing for their vote to be effectively ignored (by voting for a smaller party). So a vote which under a proportional system would be in opposition to socialism does not register in a two-party system. The winner-takes-all system results in a two-party system which makes it impossible for non-monarchist liberals to reject socialism so then over time (assuming the electorate is not communist) a two-party system will be more socialist than a multi-party proportional system. The people will be more liberal than the two parties in a first-past-the-post system. It is a cost to liberal voters to force or compel them to vote for the monopolist centre-right party and this cost will result in less support for the parties which oppose socialism. There is no advantage in assuming the voters are not liberal (assuming that democracy is communism) because even in doing so there is no advantage to be gained... when we choose between different systems of democracy we must assume that the people are liberal not because they necessarily are liberal but because there is no possible way to 'punish' the voter by reducing their choice. Trying to coerce the voter into voting for a particular party (to justify fptp) has the bad outcome of repelling voters from the democratic process. If we are to have democracy then we must assume that voters are liberal and not communist or fascist (otherwise we are advocating monarchy). First past the post does not prevent against fascism (if the people are fascist at least one of the main parties would be fascist as well) and so there is no reason not to use a proportional system.