Is not reporting a crime a de facto enabling of the criminal to do future crimes?

Be it big or small if you know of a crime that has been committed and fail to report it, is that not a de facto support of the criminal to do more or continue committing the crime? I.E. if you know someone is abusing a senior citizen or a mentally challenged person but say nothing are you indirectly enabling the person to still commit the crime of abuse against the senior or mentally challenged person? If you were sexually assaulted but said nothing are you indirectly enabling the perp to attack someone else, because his/her criminal or bad deed will not be known for anyone to prevent it from happening in the future? It will be as if they will be so remorseful that they will stop and never commit another criminal act, OK, maybe one in a Blue Moon will stop,