Importance of Kanban work-in-progress (WIP) limits

Traffic Jams! For some it is the bane of driving. Accidents, construction, reduced speed zones are all some of the root causes. But did you know of Phantom Traffic Jams? For no apparent reason the traffic slows to a crawl. No accidents or lane closures and there is no easy way out. Researchers have linked such phantom traffic jams to traffic density and variations in driver behavior. A trivial reason such as a driver braking too hard, can cause a phantom traffic jam 8 to 10 kms behind. And this traffic jam takes a life of its own. You could spend hours within that jam. So what does phantom traffic jams have to do with WIP limits on Kanban for software development?