The American political system is an oligarchy that is fashioned as a two-party system. The reality is that democrats and republicans are not much different when you really get down to the bedrock of what they are.
Libertarians, despite having a political party, often feel politically homeless due to the fact that most people have been conditioned to vote for either democrats or republicans. So they do what they feel is right to influence each party, usually to no avail.
In a true market place of ideas, there would not be this bitter dichotomy between two supposed parties.
People free from the ensnarement of an oppressive system would elect to have freedom for themselves as well as their community rather than support a meretricious political party that only focuses on repressing their imagined enemies.
Spoiler alert: the political system oppresses everyone, not just the people you've been conditioned to despise.
Feeling the impending doom that one party may dominate the other on the campaign trail, the lowly voting class picks one of the two major political parties. They are called left and right, but upon sober investigation, they are both authoritarian.
Libertarians, independents, and voting anarchists typically will defensively vote so that the lesser of two evils stay out of "public office".
Anarchists like Lysander Spooner claimed that you are no more free than a slave simply because you're afforded the symbolic gesture of choosing your master.
Enlightenment thinkers, such as John Locke, argued in favor of voting because it precluded de facto rulers and arbitrary authoritarian concepts such as the Divine Right of Kings.
Either way, with the political system being as corrupt and disorganized as it is, something has to be done.
While some advocates of voting reform have presented ideas such as Approval Voting, essentially assigning value to each topic or candidate rather than just a vote for or against, which is a vast improvement.
Nevertheless, there is still an inherent flaw that needs to be acknowledged.
In order to be a true democratic republic, the public at large need to have the option of voting for none of the above. If people do not have the option to reject all the current choices, then they are merely choosing a master. It is simply a form of intimidation to preserve a dead-end system that nobody really wants.
Ultimately there are better options than voting to make sure people get to live by the laws that they want without having to serve a despotic ruler, but if we're going to have a political system at all, it needs to have the appropriate checks and balances.. such as having the option to elect no one for any given position.
A true "government by and for the people" would have a self-destruct button if it ever approached tyranny, which was indeed written into the constitution. And here we are...
If you agree that voting has its limitations in a free society, check out What is Anarcho-Capitalism?