The short answer is that the owner has said that that is the way they want it.
Adult content has a tendency to bring a place into a different realm - one of seediness. It also chases away advertisers and probably cuts down on the value of the site.
Bars are adult venues as well but that does not make every place a titty bar - thankfully.
It would also make the place even more of a sausage fest than it is now.