It seems that most editorials about John Maynard Keynes are have an tremendous political slant and are generally done by those who have never even read this book. Primarily they are against his core conclusion that broadened government participation is required in the economy for stabilization functions. The key to comprehending Keynes is the idea that at unique times in the business cycle, an economy can become over-productive (or under-consumptive) and consequently, an agressive spiral is started that results in considerable layoffs and cuts in production as businesses try to balance aggregate supply and demand.
Thus, full employment is simply one of several or multiple macro equilibria. If an economy reaches an underemployment equilibrium, something is necessary to enhance or spark demand to generate full employment. This something could possibly be business investment but The General Theory Of Employment states because of the logic and unique characteristics of investment choices, it is less likely to rapidly reestablish full employment.