Forum admins put that rule link at the top of most boards, so they can skip a temp-ban and go straight to a permaban for offences, citing that you broke the rules, and because of the sticky and/or link being very obvious, did so wilfully. So when you come to appeal the ban because you didn't know that, for example, you couldn't have an ampersand in your post title, or couldn't mention certain words, ever; they say "you lie, you knew. The rules sticky is at the top of every board."

Boom, legal defence for enthusiastic banning.