To use (50) to scan charts for divergences or support you often compare to price. When you see price (in the case economic data) going up and going down, that is what we call divergence. When you have Price up and down, that usually calls for a top and future pullback. Using with Industrial Production we can call a recession before a recession is underway. Being able to see a large divergence between Economic Data and , we can also assume a major market correction is under way.
The aftermath of both the tech bubble and more recent financial-housing bubble bursting has really caused headwinds in % labor force vs (able body) working population. The most common theme behind the 15 year drop in % labor force, is businesses have slowed investment in human labor and have invested more in efficiency in production. What does that mean? Not only are businesses finding locations out of United States with the least cost of production, Technology is taking most of the jobs away and allowing businesses to make more profit.
If we study the chart we can see RSI (50) was signaling that we have a problem before there was a problem.