Voters stay home when candidates don't offer a message that engages them- it's not reasonable to expect people to perpetually turn up at the polls whether the major parties offer them anything or not, especially since the Democratic message never seems to move beyond "stop THEM!".

It didn't even move beyond that after the 2008 election, when Democrats HAD 'stopped THEM!" to the degree they could, and it was up to the party to find some way to actually engage the Obama movement and the millions brought into political and community involvement by Occupy and do so in the form of the partnership implied they would have with his administration, rather than the purely dismissive and destructive approach the Obama team used instead of that, which was to effectively say to the activists, the moment the votes were in, " we don't want to hear a damn thing you have to say, we're not going to give you any say, any place at the table, and you never had any right to expects us to treat you as anything other than silent, powerless, irrelevant drones".

The lesson is clear- Obama won in 2008 when he treated activists as people who mattered- he lost Congress and the party collapsed in the state legislatures over the next six years because the activists were ignored, dissed, and locked out in the cold.

Democrats can't win without activists and activism- can't win without connecting with idealism and encouraging popular mobilization., can't win by treating the young, the idealists, the grassroots, and the cities as if they owe all and are owed nothing, while treating a tiny, insignificant sliver of uptight suburban misers whose main concern is preventing anything from changing as if they are the only voters who matter.

2000, 2004, the 2010/2014 midterms. and 2016 prove that the "suburban moderates" strategy is a dead end.