Hives are being challenged all the time. Only when one is overrun, that a frenzy starts. They attack this one weak hive first, then the chaos carries over to other hives not strong enough to defend themselves. And yes, occasionally hives that would of never been robbed, get over powered in the ensuing robbing.
I never said to do nothing about it. But if you got three hives, and one starts a robbing event and gets cleaned out, it probably was not strong enough to make it through winter anyways.
In nature, a colony getting robbed out may be hundreds if not thousands of yards from the next colony. So robbing events are individual events and is natures way of culling out the weak.
Beekeepers happen to string huge numbers of hives next to each other. So something such as a robbing event, is now multiplied many times over as additional hives get caught up in the frenzy.
point is....your the beekeeper. make sure your hives are strong, equalize if needed, and cull out the weak as nature intended.