Executive teams replete with functional experts (CFOs, CHROs, etc.) are so common today one forgets they were not always the norm. In fact, they date back to GM’s Alfred Sloan, who brought together a handful of business unit (BU) leaders to address company-wide issues. This model of a small, BU-leader-staffed team was the model for many decades, although some companies named a COO to act as an intermediary between the CEO and the BU leaders.
"The Ballooning Executive Team" is from hbr.org, published on July 21, 2016.