Reddit didn't sit down and have a long debate and discussion about what is good and what is bad.
Instead, Reddit has only banned things when they have been dragged kicking and screaming to that point, and then they ban the things in a pretty narrow way.
Doxxing has a pretty bad history on reddit; I forget the exact time when it became against the rules, but a bunch of shitstorms had started up by people forming internet mobs to chase after people they thought did something wrong.
So they banned doxxing.
Similarly, Jailbait was only banned after Anderson Cooper started talking about it on the news. There didn't seem to be a long discussion of what was and wasn't allowed and what makes consistent policy; instead it seemed (as an outsider) to be "what rule can we make that blocks jailbait and its clones and as little else as possible?"
When you see the historical reason, it's clear why the stopped doxxing while tolerated creepshots: they hadn't made a rule about the latter.
The people that hated creepshots saw all this and decided on the obvious strategy: make creepshots as unpleasant as possible for everyone involved. I think it's a pretty bad way to set policy, but it's the only path that reddit had laid out, so they took it.
In the end, reddit probably should have a policy board that decides what is and isn't allowed and have long debates and discussions (partially in public) about how to set up a sane policy.