Not necessarily. Even pg will agree that a lot of the things that make a startup so productive and exciting fundamentally break when you have 15,000+ people.
I don't know if you meant it like this, but the original sense of "prove" was more like "test". That is, an apparent exception is a test of the rule's generality.
According to that wikipedia page, Nucor believes in decentralization and objective metrics, so they are indeed a good test of the rule. If that page is accurate, Nucor employees can't get very far on politics alone.
Well then, let's hear it from pg.