This is a good point. What about a person who has a pattern of accusing multiple people over time? If each of the accused individuals are all not accused by others, would this undermine the accusers credibility?

I wish this was hypothetical, but I once worked with a person that had 3 individuals over 2 years fired for this. Eventually they went too far and HR had to come to grips with an obvious mental illness being the root cause. This person was a great engineer and a good friend, which made it even harder for me and others to admit to ourselves the delusional nature of the claims.