Strong disagree. I am reminded of the quote: "If you don't have a plan of your own you'll become part of someone else's plan." Your job has as much of an influence on who you become as you let it have... the contention that you are your job really shows nothing more than a lack of ambition.
I don't think it's crazy that what you do for half your waking time has an effect in shaping you? It's like saying you're immune to advertising, you probably don't even notice all of the ways your work influences you.
Not sure where you have worked, but that's not most people's experience. You can have all the ambition in the world and with the wrong environment or culture you will slam into a brick wall very quickly. And sure, you can change jobs if your skillset is in demand, but guess what-- most other orgs function exactly the same. In fact, the people who are willing to compromise themselves most are often the ones who get ahead. That might be what some consider "ambition."
