If the "trusted decision-makers" can make a final decision that does not included the most popularly approved ideas, is it really democratic?
As long as the complete Dotmocracy results are easily available to be reviewed by the public (i.e. published), the transparency of the process makes it obvious when a leader is following the preferences of the people and when they are not. In effect there is a high degree of pressure on the leaders to follow the expressed will of the people.
Unfortunately the most preferred ideas may not always be practical (e.g. technical and budget constraints) and thus it is still dependent on the trusted decision-makers to make a realistic plan and to explain why it includes some agreed upon ideas and not others.