Would you rather try to read through one huge lump of rules, or be able to select and read through specific sections?
It makes it more organized, each page more concise. It also helps when needing to reference it.
Let's say, for example, you made a post that broke the blacklisted subjects rules.
When you inevitably say "Why was my story deleted?!!!111" someone can easily provide you the blacklisted subjects section as reference.
Otherwise, you'd just be slapped with The Rules™ and made to figure it out yourself.