I disagree that if you can't do the job of the people 'below' you, you're not qualified to lead them. When I first lead a team, I worked with people that were a lot more competent in specific areas than I ever will be. In turn, I could still learn from my 'managers', but in different areas than where I have my skills. So everybody learns from one another.

I do agree that motivation is very important. I had to think of theory X or Y. Do you distrust (X) or trust (Y) people to do their work well? These believes tend to be self-fulfilling, but can still be useful in different situations. Distrust tends to lead to a lot of control and micromanagement, which imho for knowledge workers does not work. Trust has advantages and for me leads to a better working culture, but can also lead to the issues described in the article.

I learned a lot from an online version of Harvard's Psychology 1508: The Psychology of Leadership given by Tal Ben-Shahar. If you can find it somewhere (there are some classes on youtube), highly recommended!