It's not that simple, one party would still prevail and be backed by those with the ability to control the narrative, i.e. buy them out.
Your last statement is not correct, one ideology is being pushed via 'media' both social and professional, everywhere, and it's not conservatism. Explain why 'media' backs every leftist policy and shuns or outright attacks any conservative ones? The money and the power brokers behind them are attacking conservatism and the constitution, and they are using mostly lefitst politicians to do so, they own them.