https://www.wired.com/story/facebook-oversight-board-bylaws/

Mark Zuckerberg is the ultimate decisionmaker at Facebook—he is not only the CEO, he also controls a majority of the stock and cannot be overruled. He always gets his way.

No example proves this more than his stance on political advertising. Per his command, Facebook allows politicians to say anything in ads short of illegalities. They can lie with impunity. It’s a controversial, maybe indefensible stand. Employees have begged him to reconsider. Legislators threaten that it’s a big reason Facebook should be regulated. Critics charge that it’s proof that Facebook is breaking democracy. Hillary Clinton has called him an "authoritarian" because of his policy. But Zuckerberg is adamant that it’s up to Facebook’s users to determine for themselves whether politicians are lying. So, no fact-checking those ads.