Again, I can't discuss the current execution of the rules, since I'm not involved in it, but allow me to clarify what my (and, I believe, general) understanding was around the time of the rules' creation:
For a moment, let's pretend that CN/AR doesn't exist. They're a special case to which I'll return later.
Our forum is supposed to imitate a content-liberal-but-still-legal medium of a more traditional type (like a TV station). On such a hypothetical station, most content would be generally allowable in the right context. For example, you wouldn't get banned for discussing the history of racial slurs and naming them plentifully as part of that conversation. However, you would probably have your post moved elsewhere if your contribution was nothing but a slew of insults and threats. Now, pornographic or otherwise graphic content wouldn't work quite the same. Usually, the expectation would be that the imagery be at least partially censored in most cases.
CN/AR is where it gets slightly trickier, because most contextual clues for rules execution no longer apply. This may things seem contradictory or poorly thought through, but to me it's a sensible balance between no censorship at all and thorough censorship of anything and everything that someone may consider controversial. On the Internet, it's quite feasible to run into a swastika while browsing relatively uncontroversial sites (let's use Wikipedia as an example). It is, however, extremely unlikely for one to encounter (uncensored) porn or gore within the same context.
In the end of the day, I believe it was always a general consensus that CN wouldn't really have a strong set of rules or guarantees surrounding it. We have on several occasions explained that CN and AR come with a content advisory, and that people will need to make their own call for whether or not these boards are safe to browse at their workplace/school/indoor soccer hall/bar. We have also offered the option for people to opt out of CN/AR access if they feel that it affects them negatively in other ways.