The thing is, those are only most of the reasons that are directly related to the job itself. Perfectly understandable, considering the goal is to tell managers how to retain employees. But anyone in that position should also be aware that any employee's real list includes a bunch of things that have nothing to do with anything that happens at the company they work at. The "Shields Down" moments may include things like:

Wanting to move to a different area for any number of life reasons

Wanting to change to a different career entirely

Need to take time off to deal with a new child, a sick relative, etc.

Finding an opportunity for something you can't offer them, like a chance to start their own company

And about a hundred other things that I couldn't imagine.