The framers of the constitution neglected to ban political parties, as it would infringe upon freedom of speech. So political parties monopolized the vote.
Any third-place party can always combine with the second-place party to become the new first-place party.
Therefore, our system can only represent two choices on any given topic.
Therefore, there’s no "middle ground party" in politics.
(This system is however vulnerable to sybil attacks and fake pledges).
But power continues to coalesce in central authorities.