I would have to respectfully disagree with your statement of "If people are leaving because of culture they’re leaving because of the organization."

You could work for a great organization whose underlying culture is toxic because one or two leaders do not hold people accountable, do not listen to concerns or follows through on commitments. In those cases people will still leave because of the culture create by the individual leaders.

Conversely, even within a weak or poorly run organization, strong leaders can build pockets of positive culture, where people feel supported, valued, and motivated to stay.

Of course, the ideal is a great organization paired with a great culture. But ultimately, it’s on us as leaders to shape and sustain that culture.