I think it's because of just saying 'don't post kiddie porn or kiddie porn art; fiction dealing with the subject will be subject to the Miller test' and maybe giving links to information on the Miller test they take about 15 paragraphs to say that so it all gets a bit lost in the mass of words.

But I do think that there's also a distinct element of people not wanting to be able to read or not wanting to understand, and generally lacking common sense.