The point is that if it does represent the will of the people and the people in power don't like it, the will of the people will still lose out.
The two party system in the US is a problem, but it turns out it's natural consequence of Democracy. There's no law against other parties, it just turns out that with direct voting in a large country, over enough time, we arrive here with two parties.
If you look at the Democratic party, in 1968 an unfavored candidate was nominated based on votes, and so the DNC decided to institute the concept of super-delegates from thereon out. They did this because letting normal democracy run its course didn't work because the people elected someone the party elites didn't think was the best. The super delegates composed of party loyalists and high ranking party members that could ignore DNC votes. This essentially gave the party more control over who would win and removed voting power from normal people.
In the current election, Donald Trump is doing the same thing to upset the Republican party leadership. The Republicans haven't implemented anything as undemocratic as super-delegates yet, but if Trump wins they might be encouraged to (since it's the type of Democracy-giving-poor-results scenario people in power try to avoid).