I actually think it's a fairly major problem for several reasons: (1) Nonprofits may be led by folks who are really passionate about the cause but who have not really focused on honing or developing their leadership skills, so they may not know HOW to foster personal growth and development in their teams. (2) Professional development resources (both time and money available for it) are usually pretty slim, so often programs get every last dime instead of staff development. (3) Nonprofits usually have very flat organizational structured, meaning there really isn't much of a chance to "move up" for many staff. I think that fear that folks will "move out" instead may keep leaders from really building their teams and instead keep people siloed.