This is usually not true for successful companies, but it's especially not true in facebook's case. Mark Zuckerberg has kept incredibly strong control of facebook, holding more than 50% of voting control even as it's grown to a half trillion dollar company - so he definitely deserves credit for what his company has become.

Also, he has made some strong, unintuitive decisions along the way (no advertising in the first several years, real name policy, dropping out of college, moving to silicon valley, hiring experienced tech executives, buying a dead-simple photo filter app for 1 billion dollars) that can directly be attributed to facebook's success today. It's hard to remember today, but in the first ~5 years of Facebook it was very far from obvious that facebook would dominate the social space.