I can't answer for America, but generally in democracies you get two and only two parties. Anyone taking a middle position cripples the side they're closest to.

Before Socialism was a thing, England had 'Liberals/Whigs' (what yanks would call libertarians, because they've somehow managed to repurpose the word liberal to mean the opposite of what it means) and 'Conservatives/Tories' (king and country and church and don't change things because you'll break them and hurt people).

And of course, like all political groups do, they hated each other.

The Church of England was once known as the Tory Party at Prayer. The Liberals were the radicals, the party of industry and progress and free markets and who cares who it hurts as long as it's the future.

With the rise of socialism/fascism/anarchism/progressivism, a truly radical program to rebuild society on utopian lines and use totalitarian terror to enable even more freedom and progress and human happiness, represented in England by the Labour Party, the 'conservatives' and 'liberals' were squeezed, and combined to oppose socialist thought, which hated them both and wanted to destroy everything they thought was worthwhile in the world.

So there came to pass an uneasy alliance in England between classical liberals and religious loonies, who'd naturally detest each other.

That's the modern Conservative party, who want to use radical social transformation and the power of the free market to go back to the glorious past, and are very much in favour of freedom of speech and thought as long as it's the sort of speech and thought that they approve of.

The Liberal Party effectively ceased to exist, because in its radicalism and desire for progress, it was more sympathetic to socialist thought, and so it got crushed.

Socialism has rather collapsed as an idea after an hundred years of practical experience with utopia, leaving Labour as the party of 'every problem can be solved by stealing more money and spending it on subsidies'. A position which is popular with those who benefit from subsidy, and unpopular with those who get their stuff stolen.

And of course, few of the people in either party actually believe in the causes they publicly espouse. They're not stupid. But public communications have to be simple-minded and rally tribal support.

Obviously this is a terrible system, but it's better than regular civil war, which is what you get in all other systems of government.