It seems to me that political parties exists solely for the purpose of concentrating and funneling contributions for candidates and propositions. If there were no political parties, Sherman Adelson and the Koch Brothers would have a much more difficult task attempting to make television and print advertising buys.
I no longer make contributions to political parties, partly because I detest all political advertising and because I feel that every candidate I have ever supported as let me down in a big way. Consequently, instead of calling myself a Democrat, I see myself as a left-leaning Independent. I will probably continue to vote mostly Democratic (while holding my nose), but do not have any interest in their marketing problems. All political telephone calls are quickly dispensed with: “I’m sorry, I view myself as an anarcho-syndicalist and your candidate is just not toeing the line!”
Why support a gang whose primarily role is to get my vote at any cost, and then proceed to turn every political promise into a prevarication? As if the whole spectrum of American politics can be compressed into the platforms of two political parties! Let there be dozens of parties: It would force them to talk to one another.
If you think this is impractical, turn your attention to Iceland, where the fastest growing party is the Pirate Party.