What's the point of the rating system if even dictionaries have to be rated 17+? Wasn't the idea to allow finer-grained control over the content allowed on a g

What's the point of the rating system if even dictionaries have to be rated 17+? Wasn't the idea to allow finer-grained control over the content allowed on a given iPod/iPhone than was possible previously? Why can't they allow filtering over the sub-categories rather than just the broad labels? There's a world of difference between "obscene" words and graphic pornography.