A company is more than the personality of its CEO. Gates, Zuckerburg or Elon's personal faults shouldn't override the work and mission of thousands others.
It often does though, which is why having the right people in high positions is important. The CEO is the face of the company and for better or worse the company will be judged by their actions to some degree.
I would argue the exact opposite. Companies like Amazon and SpaceX have shaped their entire company culture using the values of their respective CEOs.
It depends on the CEO. I think SpaceX reflects more on the culture of the COO than the CEO; the company does not operate like the CEO does.
A company usually mirrors the values of its executives. You're right it shouldn't override the mission of the many, but the faults are baked in there somewhere.