To build on this analogy, tug of war fits a bit better. Nothing dramatic happens if one person let go, but if half of one team just let loose at the same time without communication, bad things happen.
In the Tacoma example, the input frequency continued to add onto the bridges motion which ultimately caused it to destroy itself. In an electric grid, a misaligned phase can cause excessive spikes (imagine 480V when you expect 240V) or the generators to ultimately burn themselves out because 2 generators are fighting with each other, one trying to raise the voltage while another is trying to decrease the voltage. The really tricky thing is that load (particularly inductive or capacitive loads) look almost exactly like an unaligned generator.
Communication that detects the release and travels as close as possible to the speed of the natural signal in the rope, and is robust enough to recover without losing stability if the other team grabs the rope again while your "let go" signal is mid-flight.
One way to dampen this is to put a really strong guy on each side, with instructions to never let go of the rope. These are the flywheels of the grid.