I think that a political party is a collective, a union of voters, coming together to more effectively describe the principles and values that they hold and to help them achieve governance that reflects those values.

To say that the foremost and overwhelmingly most important purpose of a political party is to elect its candidates is wrong headed. It subordinates its purpose to that of its candidates. It should be the other way around. The people through their union of principles and values demand good governance from the candidates and elected officials they endorse.

The purpose of a political party is to assist their members in finding and promoting candidates that adhere to their principles and values. And holding elected officials to policies that align with those values and principles.