The whole concept of mass market celebrity is largely the product of American post-WWII prosperity and the explosion of a consumer class. It was rare prior to 1950 and arguably peaked around the early 2000s, when mass media went into steep decline.
Most "celebrities" alive today would have been active (or the topic of public discussion) during that period. So should we really be all that surprised that, as the Boomer generation rapidly approaches peak mortality, celebs are also dying in greater numbers?
The article concludes that this year was a "once in a century" outlier. On the contrary, I predict an even more grim 2017. Regardless, this analysis is incomplete without at least a cursory discussion of the distribution of celebrity birth years. Line that up with an actuarial table and then tell me how anomalous 2016 was.