Nation-state actors conducted information warfare on Facebook's platform. Solely blaming Facebook for that is a little like blaming United & American Airlines for 9/11. They are just the most obvious attack vector, but it's a failure of government to allow rogue actors to act freely. Unfortunately after we've created the internet equivalent of the TSA we may find the cure worse than the disease.
They showed malevolence when they deal with the errors they made. That makes them the worst among the biggest companies.
Facebook has good "We are sorry,errors were made." PR game but it's not sincere.