Thirty years ago, the publication of Barbarians at the Gate — the inside tale of KKR’s 1988 buyout of RJR Nabisco — chronicled the apotheosis of a form of capitalism in which shareholders reigned supreme. Three decades later, cracks are showing.

A major debate is now underway on how to rebalance the interests of different stakeholders, a debate made very challenging by the prevailing political and economic winds.

The...