Everybody would like to answer that question, I'm sure, but I'll be brave here and say that it can be an inhibition.
Frankly, I think for the level of national charity that is addressing you today, that's less of an issue for the simple reason that the budgets are so large. There's so much programming going on that you'd have to be very politically focused to break the 10% rule.
However, having spent most of my life working for non-profit organizations, I can tell you that the problem you are raising is a very real one for smaller non-profit organizations. Some of the coalitions that exist on mental health and other issues, by their nature, are not offering programs—their affiliates are—but they need to do advocacy work, and it is an inhibition. That's all I'll say.