What does? The necessity that you should actually show something is occurring before a company destroys someone's reputation and livelihood? Reality is that people lie. Do you genuinely believe that an accusation should be taken as 100% truth simply on one person's word? Do you not see how easily that become a weapon? Even reprimanding a person, when there's no proof they've done anything wrong, establishes a bias against them. That's a great way to alienate an employee who may have done nothing wrong, not to mention opening the thread of legal repercussion.