I would say harm vs. not harm is much less subjective than direct harm vs. indirect harm. Is yelling 'fire' in a crowded theater direct or indirect harm? Defining that seems much trickier than just defining whether it's harm.
Inaccurately and purposefully yelling "fire!" in a crowded space is a direct attempt to cause panic. In other words, you would never be prosecuted for yelling "fire!" in a crowded space when there actually was a fire. It is not the act of yelling "fire!" that is illegal, it is purposefully causing a false panic that is illegal.