In the straight porn industry, the ban on male-male contact comes from the top (i.e. directors, studios), not the bottom (i.e. porn viewers). It is a very conservative industry that has no place for little bits of male-male contact side by side with heterosexual and female-female contact.

And I'm not necessarily talking about full-blown sex between men, either. It might be a touch or a kiss, for instance. Why, for instance, can't I see Mr Marcus squeezing Lee Stone's balls as he's coming over some chick?