Kind of... but I would not say there is no system.
It's kind of like an oligopoly in business. The entry barriers are extremely high... thus the costs are high and the chance of marketing a new brand nearly impossible. But unlike many business-world examples, the party systems barriers are mostly artificial.
Plus the main way to transfer information is the mass media... which, if you haven't noticed... does not ever show third party candidates. They have policies about equal time to the parties... interestingly two parties.
While the ultimate reason for lack of third party support is the voters, it is not simply an accident and certainly not a result of all parties being equally out there.
It is as much a function of voter laziness as voter choice. The big parties know voters are lazy. The businesses they are in bed with know it. Voters know it (that's why they think a vote for third party is a wasted vote)...
But that's not to say the deck is not artificially stacked in favor of the big parties... The question I have is "Why does it have to be a function of money?" It doesn't. But it is. We are a civilization raised with consumerism as a primary mode of identity. Our politics is consumerism.

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