It's one thing to advertise a service, and another to advertise a website. If you want to advertise a website within a community, there's always the hard way to do it: add quality posts that bare a signature. That way the forum gets activity and content, you stand a chance to get some visitors.

Rules like the one at WHT came about as website owners started to abuse their ability to advertise, basically resulting in them getting traffic to their sites and competing on a certain level with the forum, without giving anything in return.