This is not to say that porn is without economic value. But it's effects are often exaggerated. It is often claimed, for example, that porn is a primary driver of adoption for technology such as internet access and VCRs. This is about as sensible as claiming that the proliferation of cell phones is a function of dial-a-porn. Yet these claims are routinely made and broadly accepted because porn is widely available on any platform.
In fact, the exaggeration of porn is a fairly common phenomenon. Many people think of porn as an important driver of free speech litigation. This is only true if we stipulate that folks such as Lenny Bruce practiced pornography. Yes, there is "the People v. Larry Flynn." But that case is actually much less important as a free speech case than one would imagine from the fact that there is a movie about the Penthouse case.
My bottom line is that people, for various reasons, like to believe that porn is more important than it is. It confirms something about human behavior for them. But the evidence is simply not there.