One of the things I love about startups is feeling like my input is partially responsible for the mission, culture, and direction of the company. I can't imagine doing work for a company that was doing something and not feeling like I'm making a contribution to that goal.

Maybe you're right and developers at FB don't see that they have any responsibility or input towards what FB does with the tech they build, but I hope not. It would be horrible to be that detached from the outcome of your work.