There's no point in arguing semantics without being clear on the definitions I'm using. I use "politics" to refer to the practice of participating in an organization that governs. By "governs," I mean has the legal authority to exercise physical control over a region or group of people. In the context of modern Western nation-states, I use "politics" to refer only to participation which is condoned by the government. So I consider voting, running for office, helping with election campaigns, lobbying, etc. to be political acts. I don't consider other attempts to influence governments to be inherently political acts, like civil disobedience, participating in black markets, and other forms of counter-economics.

Obviously, in the broadest sense, anarchism is relevant to political philosophy because it is the suggestion that governments and therefore politics shouldn't exist. Analogously, atheism is relevant to religion because it is the suggestion that religion is incorrect. And yet, with the definitions I'm explicitly using, anarchism is not politics and atheism is not religion.

And to be clear, there are certainly anarchists (and, much more commonly, minarchists) who blatantly use political methods to achieve their desired results. A prominent example would be Ron Paul, who is arguably an anarchist, but seems to believe that using the condoned political methods to move the USA toward a smaller and more constitutional government is useful. I disagree with these people.