I have been very quiet about Americans Elect, the organization that obtained open lines on the presidential ballot in 29 states, reserving those spots for whomever its members chose as nominees for president and vice president.

On the one hand, I disagree with several aspects of the organization’s diagnosis and strategy. On the other hand, their leaders were kind enough to meet with me early in the process to discuss youth participation, and my lengthy discussion with them gave me confidence in their motives and made me doubt the most hostile attacks. Yet I couldn’t really rebut those charges except by citing a superficial personal relationship, which needn’t persuade anyone else.

Now that they have decided not to field a nominee, I feel more free to comment.

One take on Americans Elect is that they want to be a moderate alternative to the polarized Democrats and Republicans. I happen to believe that the national Democratic Party is a moderately conservative one, that there is little daylight between the two parties, and that the only space left between them should be filled by the Republican Party itself, once its moderates strengthen their hand. So I am uninterested in building a centrist third party. On the other hand, the Americans Elect website does not prominently cite either moderation or centrism, and its leaders emphasized to me that their ticket could be taken by, for example, a Democrat and a Green. They required that the two nominees come from different parties, but not necessarily one from the left and one from the right.

Another read of Americans Elect is that they wanted to offer voters an alternative because both major parties had failed. That is closer to their own rhetoric and I don’t completely disagree with it. The problem is tactical. In a close presidential reelection race like the one we face in 2012, a third party is just a spoiler. Anyone who votes for the third-party candidate is actually helping Obama or Romney but cannot know which one. That is the opposite of empowering; it means giving up your vote for a random draw. A case can be made for greater political pluralism, but a close presidential reelection campaign is the worst time to add a third choice.

A different interpretation is what the leaders stressed to me. They argued that the major parties’ nominating systems are corrupt and broken. Why, after all, should one state vote at a time, starting with two almost entirely white and heavily rural states, and reaching California and New York well after the contest is over? Why should you have to vote on one particular day but register a month before? Why should the “money primary” (the race for private funding) be so important?

By getting on the ballot in 29 states and promising an entirely different nominating process (online, deliberative, simultaneous), Americans Elect reminded us that alternatives are possible. Our political system is the oldest in the world and is now sclerotic and corrupt. We take things like the parties’ nominating systems for granted when those are eminently changeable.

The main reason Americans Elect failed to field a candidate was the unwillingness of serious contenders to participate. Some presumably preferred either Obama or Romney and didn’t want to play a spoiler role. Others were put off by the prospect of a national race that would require half a billion dollars to be reasonably competitive. The campaign finance system of the general election is beyond the control of Americans Elect and represents a very serious obstacle to decent politics. But the experiment did remind us that our existing national parties could completely change their own nominating processes. At this point, the question is: Why don’t they?