I could agree if by "participate" you mean come in as the CEO and clean house, like what happened with Uber when Dara took over from Travis.

You might possibly be able to do something as a high ranking HR person, but as a L5 engineer, the amount of cultural impact you can realistically impart isn't that big.

Changing a company's culture is nearly impossible at a startup, let alone a behemoth like FB.

Google did just vote to unionize, so it's not impossible, but very difficult.

Between 200 and 300 Google employees formed a union. Google didn't vote to unionize.