Yes, an individual was responsible: the CEO. Ultimately that job comes with the responsibility for everything happening inside the company and as a CEO you ensure that you have the proper culture and control mechanisms in place that that sort of thing does not happen, and that if it should happen that it gets detected.
By your standards, zero companies have a proper “culture” then. That’s just not how things work anywhere. You might think or even assume they should, but they don’t.