Sometimes someone is just to blame though.

Finding a scapegoat is obviously an awful practice, even though many companies do it. But the opposite is just as useless: you end up doing a bunch of mickey mouse bullshit "process improvements" that make everyone's job harder while everyone avoids talking about the fact that Tony should never have been allowed within a hundred feet of a forklift because he's a terrible driver.

Typically in our after action reports we're good at finding both the systemic and human error causes of issues. And the root cause of most issues is not human error per se, just unintended consequences of what seemed a good idea at the time. Which should not be punished (unless someone was just being really stupid). But sometimes an incident is a result of a total failure to do your job - cutting corners, going through the motions without thinking, failing to notice something that's obviously wrong, etc.