Quality senior leadership is, indeed, very important.
However, far, far too many people see "their company makes a lot of money" or "they are charismatic and talk a good game" and think that means the senior leadership is high-quality.
True quality is much harder to measure, especially in the short term. As you imply, part of it is being able to choose good management—but measuring the quality of management is also hard, and most of the corporate world today has utterly backwards ideas about what actually makes good managers (eg, "willing to abuse employees to force them to work long hours", etc).