I think Facebook serves Democrats better in the sense that inconsistent voters are more likely to go vote with little pushes from social media, where as the Republicans I know (non scientific assessment here...) are all weirdly hardcore about voting and will likely already be voting anyway.
In other words, Democrats are more likely to pick up new voters with tech persuasion than are Republicans. And social networks are great for finding new voters with info mining.
And not to be too political here, but Republicans need to embrace change because their voters are going to all die out while they make the youth the scapegoat of our problems and debt, which just solidifies the Democratic voters for life into their old age. Not to mention the old people sucking out the ss and medicare are the actual sources of our financial shortfalls, making them all seem hypocritical.
That shining city on a hill stuff seems to have devolved into a message of hellscapes and doom to all humanity if we don't choose the Republicans, and it seems pretty petty to me instead of just talking solutions.