I have to agree that management is difficult. It's a challenging task to coordinate the work of individual contributors who aren't paid or committed to schedules, etc.

But all this is saying is that there are very few individuals who are willing to work on managing open source projects. Or at least they don't get in contact with the projects they could help with.

Open source projects need more contributors than just programmers, but how to achieve that is a hard question. Programmers don't make good artists, UI designers or managers, but finding individuals who would like to contribute is an issue.