I know a huge bank that had problems that every developer they promoted, quit.
It was because their managment positions were so stressful and so communication heavy, that most developers were totally not suited for it, and just plainly quit.
Technical types tend to think that there's not much to the task or process of motivating and managing a team.
The people that promote individuals into management roles are often just as naive. The individuals are expected to develop new skills simply by virtue of having been promoted.
