You start telling yourself the story of your organization the day you're hired. Over time, the story becomes more complete, but also more constrained. As you start to "know" more, the range of possibilities narrows.
But what do you really know?
We don't recall everything that happens. We can only store what fits into our mental categories. As soon as you start forming those categories, you start reifying them, choosing what to keep and what to dump out of your mental file cabinets based on what meshes with the story you've already started telling yourself.
You see this most frequently with a long-time employee shooting down a new idea without even considering or discussing it: "We tried that and it didn't work."
And maybe that person is right - the organization DID try it and it DIDN'T work.
But maybe "it" wasn't done right or by the right person or at the right time. Maybe the audience or the environment has changed in the interim, but because different people and different circumstances don't fit into the long-timer's story, s/he hasn't noticed.
This is why people get so excited about the concept of beginners' mind and why so many new hires try to retain their outsider perspective as long as possible.
I'm not arguing that you need to change jobs every two years - there's value in institutional memory as well.
What I am saying is that, if your story is stale or you feel it's completely filled in and can't accommodate so much as a change in punctuation, maybe it's time to move on and recapture that blank slate.