Why does Everyone on Answers in the Politics Section ume there are Only TWO Parties?

Everyone umes I am a Democrat because I oppose the greed that runs rampant in most capitalist societies and I lean more liberal on social issues. Truth be told I am more of a conservative Libertarian, so why does everyone act like there are only two parties? Have the news networks embedded that into our minds that much? Are there any others who hold a third (or forth, or fifth) point of view on these matters?