The best (but not perfect) answer I've seen yet was in this article:
.... What (liberals) really want is liberal Sharia law, a secular theocracy. The minimum wage, gender equality, nationalized health care, and global warming—whatever their practical virtues—are not just expedient policy prescriptions. They are essential aspects of the liberal fatwa. Feminism, deconstruction, and gender theory are not just academic abstractions up for discussion among liberal academics: They are articles of their religious creed. Question them and you are not just wrong—you are a heretic.
You wonder why the left is having a nervous breakdown in the wake of Trump's election? It is because, for them, politics is the means to secular salvation. This means that, to them, political failure is not just a setback on the road to a more stable society—it is a blow to their very worldview. Opposition to their program is not just wrong-headed, but evil.
This is why all of the excesses of these demonstrations—death threats, looting, violence—can be excused by CNN and MSNBC: They are the necessary extreme measures, justified in light of the threat to their ideology.
The only thing I can add to this explanation is that the left is feeling (wrongly) that there is more of them than Normal People, and this safety-in-numbers approach begets unmasking. Indeed, look at the growth in Republican-won counties in 2016 vs 2012 and the resulting concentration of Hillary-loving statists in The Clinto Archipelago:
In short, the lunatics are on the run and coalescing in urban enclaves. Thus they have less and less contact with Normal people which blinds them to their shrinking numbers. However, this also increases the intensity of their echo chambers, spurring them on to a militant evangelization of their Secular Theocracy.
My guess is the Dolphins see this trend and decided to take action.