Keep in mind that the US uses first-past-the-post voting for many elections, meaning the party with most votes takes the entire pie that was voted for. Thus not

Keep in mind that the US uses first-past-the-post voting for many elections, meaning the party with most votes takes the entire pie that was voted for. Thus not voting for one of the two biggest parties will help that other big one you like even less. Yes, this kind of system doesn't allow a diverse set of parties.