Here is the real question: Does one of them have any authority on the other? Whether it is real or not does not matter. If, for instance, the older person promises pie in the sky to the younger, less experienced person, then any consent would have been based on initiation of the use of fraud. Especially if that pie in the sky is contingent on consenting to sex. In cases like these, we have a clear case of fraud, and this can damage people of any age level.
The other thing that can create a problem is when the older person attempts to force the younger one into consent. This is common in religions, where fear of hell or Gehenna is used to coerce the younger person into consenting to an act that they otherwise would not have. It also happens in the workplace, in prison, in households where an uncle will use perceived authority to rape a cousin, and yes even in the government. Any time the younger person is unfairly manipulated into consent, whether with force, threat of force, coercion, or fraud, a crime has been committed.
One thing I do not see as sick is when consent is given without any of these factors. It is not at all uncommon for children of ages 10-16 to develop crushes on heroes that are adults. Sometimes, adolescents can be physically attracted to someone that is older but does not look or act it. Other times, acts of unconditional kindness will set off a crush (especially when these acts of kindness are not used to manipulate the younger person into unwise consent). Much less common is when a person in his 40s bonds with someone much younger, marries, and the pair stay happily married until one or both of them die. But it happens.
What is needed here is one sweeping law: No one shall initiate the use of force, threat of force, coercion, or fraud to extract a consent out of the other partner. The ages are eliminated totally. If one person abuses his authority and coerces a consent out of the other partner, or promises pie in the sky rewards that are conditional on receiving sexual favors, it's abuse whether the younger person is 3 or 103. With that law in place, there would be no need for age barriers to be erected. There would also be no need for excess obsession of "proper touching", since the use of the above unfair advantages would be the determinant of whether abuse happened.
Note that the Watchtower Society's problem would here be magnified in severity. Just about every case of pedophilia in the Watchtower Society involves some form of initiatory force, coercion, threat of force, fraud, or all or some of the above. Oftentimes a hand is placed forcibly where it does not belong. As often, threat of retribution is used to coerce a consent (and disfellowshipping if they rat out the offenders). The pie-in-the-sky promises include living forever in paradise on earth, which the Watchtower Society itself is guilty of. Use that as the gatekeeper, and (1) the cases of abuse that do the most damage get the harshest punishments, (2) innocent people are spared from "jail bait" when an underage person tempts them into doing something and lies about their age, and (3) the Watchtower Society gets its whole structure exposed as built on initiatory force, threat of force, and fraud. Everyone wins, except those who are guilty of creating problems for others.
