Authors of the Constitution wanted to avoid political parties because they worried that these factions would cause Americans to be divided. One of the biggest advocates of avoiding political parties was George Washington.
In Washington's farewell address, he warned American citizens that political parties play on peoples passions and emotions. Along with this, he mentioned how parties can lead to disunity and that the rhetoric of these parties overwhelm peoples ability to think logically.
This is why many authors were against the idea of political parties.
