If anything, Democrats have failed time and again because they have had far more ideas amongst themselves - ranging from the very liberal to the somewhat conservative - that they have often failed to unify around a single set of ideas the way Republicans have. Don't just take my word for it. That is, in fact, one of the messages in Crashing The Gate. I'd like to point Markos to pages 173 and 174 in his own book:

Ask ten people what the Republican Party stands for and you'll get roughly the same ten answers: [...] Now ask ten people what the Democratic Party stands for, and you're likely to get ten different answers... ...As it turned out, this hasn't been a book about policies or new ideas or message, even though those are critically important in taking back our country. We like to believe the ideas that will lead the Democratic Party to a new governing majority already exist, but they need to be articulated clearly.

Markos unfortunately confused message discipline with ideas. Wrong, wrong, wrong. The Democrats have been the party of ideas, the Republicans have been the party of propaganda. That has not changed much in a long long time.

(Emphasis supplied.) It is clear that Markos has confused actually having new ideas with actually conveying them effectively in the political process - where he rightly chides Democrats for their ineffectiveness and lauds the GOP for its effectiveness. And indeed, Markos himself performed like a Democrat here, failing miserably in delivering his message, choosing to parrot a David Brooks' talking point instead of laying out his REAL complaint - the one he makes in Crashing the Gate. And this too is a Democratic curse. Barack Obama is especially prone to choosing GOP frames. As he was here, and as was Markos here.