Eve was "deceived" by satan. As such women are regarded as a conduit for the devil to reach men. That's why modesty enforced by religionists is so disparate among gender. Victim blaming becomes much easier when the foundation for it has been indoctrinated into the masses.

Humans are sexual animals. Celibacy and sexual abstinence go against our very nature, so it is hardly surprising that there is sexual activity among those groups, either consensual or coerced. One of the reasons for requiring abstinence from the religious is to test their dedication to their faith.

Those who are able to maintain sexual abstinence are considered to be more trustworthy, since they are turning their backs on a basic need of human beings. If they will submit to authority in that, they are likely to submit in many other ways. Those who fail in being abstinent have often been cast out of the organization in shame. However, failure to abstain is more common than we imagine, so adjustments are made in many cases to retain people in their orders.

The entire thing is hypocritical from the very start. Denying one's basic needs has become central to the Roman Catholic Church's basice doctrines for the religious. That contradicts the very nature of the human experience. So, it's a false doctrine, if you believe that an all-knowing deity created humans. Hypocrisy in one area tends to lead to hypocrisy in many other areas, as well.

Certainly the RCC prohibits all sexual relationships from priests and nuns, but most other large organizations prohibit sexual relationships with subordinates for different reasons. It's pretty much impossible to prevent quid pro quo under such circumstances. Usually the policy is only enforced on the person in authority. In the case of the RCC the situation is far worse because the subordinate is far less likely to report abuse because they are also guilty of a violation of policy along with the addition of a break with imposed moral obligations and the shame that goes with that.

As far as the priests go, not only do they have the authority given within the organization, but the implied authority of allegedly being closer to their three avowed deities. As such the abuse of that authority is multiplied.

The real point is that it is officially forbidden, but ignored for the most part. Only when it becomes public knowledge is anything done.