First off, they don't have the experience to get anything done. Second, they tend not to know squat about the things that need doing.
You could stop reading now; I've just told you why outsiders do not get things done. But Paul Waldman at the Washington Post/Plum Line explains why in more detail. Here's the good and the bad-ugly.
On the good side, there is Bernie Sanders who taps into that outsider thing, but who has the experience to do the job.
On the Democratic side, you can at least make a reasonable case for Bernie Sanders’ brand of outsiderism. Sanders is no political neophyte — he has held public office for most of the past 35 years, which gives him an insider’s understanding of how the system works. And his argument is a focused one, centered on the influence of big money and how it helps produce and sustain inequality. While tackling that problem is extremely difficult, one could at least imagine a President Sanders making some progress on it.
On the bad-ugly side of the ledger, there is Trump and Carson who fold like a child's origami when asked about substantial matters.
On the Republican side though, the two leading outsiders, Trump and Carson, have nothing so specific in mind. They argue that they’ll get things done, Trump through the force of his will, and Carson because he is untainted by politics. Ask either one of them about a specific policy issue, and it quickly becomes clear that when it comes to the issues a president deals with, they’re utter ignoramuses, which is perhaps understandable, if less than reassuring. I’m sure Marco Rubio doesn’t know much about brain surgery, which Carson knows a great deal about, but he’s not running for Brain Surgeon in Chief.
So here's some advice to voters.
... when it comes to things like government gridlock, you have to ask the question again: What is the outsider candidate going to do differently? Outsiders talk about things like "shaking up the system" and "changing the way Washington does business," but they seldom get too specific about what those things might mean in practice. What would a shaken-up system look like? For instance, would it mean that Congress would swiftly and efficiently pass a bunch of bills instead of being consumed by bickering?
... Fed up with Washington’s gridlock and its inability to solve big problems, voters turn to outsiders who promise to do things like "shake up the system" and "change the way Washington does business." These candidates supposedly possess fresh ideas and new perspectives that can turn everything around.
It’s hogwash. But people never seem to learn.
We could all prove that wrong by casting votes that take into account things like competence and relevant experience. You know, those things that Republican businessmen like to see in a prospective employee.
UPDATED EXAMPLE: Sarah Palin wants to be energy secretary for Trump. What she does not know about the Department of Energy would fill Trump's ego. From Vox.com:
"I think a lot about the Department of Energy, because energy is my baby: oil and gas and minerals, those things that God has dumped on this part of the Earth for mankind’s use instead of us relying on unfriendly foreign nations."
"I'd get rid of it. And I'd let the states start having more control over the lands that are within their boundaries and the people who are affected by the developments within their states. If I were in charge of that, it would be a short-term job, but it would be really great to have someone who knows energy and is pro-responsible development to be in charge."
The catch? She has no clue about energy or much of anything else. All the stuff she's talking about is under Department of Interior.
Would Trump, an ill-informed blowhard outsider pick an even less informed air-head for a cabinet position?