Running for office doesn't really work if you can't get your message out because the media and political parties refuse to declare anyone but the incumbent "electable." I've worked on a political campaign before, and also know people who are delegates for their respective parties, and the inertia incumbents have is extremely difficult to counteract.

One problem is that people with lots of money can afford to pay others to work full time in their interests, while those of us actually doing stuff with our time can't afford to spend eight hours a day in caucuses, party delegate meetings, city halls, legislators' offices, etc. trying to fight for an issue and/or get elected.