The rise of social media was somewhat preceded by the retirement of the fairness doctrine, and coincided with the rise in partisan media (1). Would a reintroduction of the fairness doctrine via legislation help in any way? I tend to think it would.
What exactly would it do? Broadcast is an increasingly uniform, bland, and irrelevant set of stock footage and scripts targeting a shrinking population. The fairness doctrine wouldn't have had any more impact on social media than it did cable.
1 https://en.m.wikipedia.org/wiki/FCC_fairness_doctrine