I think it’s mostly just a lot easier to have a no alcohol policy, than an alcohol in moderation policy.
It’s probably easier to overlook or manage occasional violations of a no alcohol policy, than it is to manage the frequent abuse of an alcohol in moderation policy.
Personally, I prefer a dry ship.
Getting back to the topic of this particular rape, alcohol was the enabling factor. It would never have happened without alcohol. The rapist was emboldened by alcohol. The victim was disabled by alcohol.