It wasn't so much "idealism" than it was the fact that social media was directly responsible for the election of Barack Obama in 2008, the US's first Black president. It also gave him a significant advantage in 2012. Nobody wanted to touch social media out of fear of putting future Democrat POTUS candidates at a disadvantage.

Notice how, in 2017, it's only after everyone starts post mortem evaluating the 2016 election that the "idealism" of social media begins to sour.