It only leads to disappointment. You really should manage your expectations better. What they say to win has nothing to do with what they will actually do.
In Barack Obama's speech the night he won the 2008 election, he made a promise:
[A]bove all, I will ask you to join in the work of remaking this nation ...
This victory alone is not the change we seek. It is only the chance for us to make that change.
And there were a whole lot of people ready to help. According to Marshall Ganz, one of the architects of Obama's 2008 organizing strategy, Obama's campaign had 3,000 organizers who recruited thousands more local leaders, who then helped mobilize 1.5 million volunteers and 13.5 million contributors. They thought Obama meant it, and was going to ask them to stay involved and keep campaigning.
But Obama didn't mean it. As Ganz later said:
One Obama campaign volunteer from Delaware County, Pa., put it this way soon after the election: "We're all fired up now, and twiddling our thumbs! ... Here, ALL the leader volunteers are getting bombarded by calls from volunteers essentially asking 'Nowwhatnowwhatnowwhat?'"
Consider this, however: I think it's unlikely that Obama's demobilization of his supporters was actually a "mistake." As Ganz put it in 2010, Obama saw his supporters "like a tiger you can't control"; Ganz speculated that the president's real goal was simply to "keep the machine on for the next election."
In other words, Obama was acting in accordance with what I like to call "The Iron Law of Institutions" -- that is, the people in charge of institutions (as Obama was in charge of the Democratic party and his "movement" in 2009) care first and foremost about their own power within the institution, rather than the power of the institution itself.
So while the Democratic party itself would have been much more powerful overall if Obama had kept his grassroots mobilized and involved, Obama himself and his most important donors and supporters would have been less powerful within the Democratic party. So Obama let the enthusiasm and activism surrounding his candidacy dissipate, all his supporters stayed home in 2010 and Obama's party suffered a catastrophic collapse.
But from Obama's perspective, so what?