The goal, as ever, is to present to the public an accurate reflection of what the people as a whole think about candidates and issues.
Can this not simply be harvested from the endless volumes of online posts made to the public internet? Why do they act like they need to go on the hunt for something that is normally difficult even to avoid?
The types of people that offer their political opinions online are not themselves representative of the whole voting public. This would introduce an instance of sampling bias.