Go ahead and search "happy employees lead to successful companies" and you will be bombarded with consistent uplifting messages about employees and happiness. Just about every content piece promotes employee happiness benefiting organizations at large.
With the article title being controversial at first glance, there were many people who work in successful organizations (speaking from a strict revenue standpoint) where employees aren’t happy. Just look at sweat factories, crop fields, certain nursing homes, finance boiler rooms, or pyramid builders (wait those were aliens). With such well- examples, who do business readers almost mindlessly follow common business slogans without questioning them?