One might have run the risk of being called a delusional pervert if one had correctly anticipated the massive scale that online sex work has grown to since the dawn of the internet.
I don't think there is really that much more porn being produced on a per-person basis, just that where they used to be Polaroids that would be lost to time now all of the porn can be distributed worldwide instantly for free. Someone who sat down and worked the numbers might have come to this realization early on, but few people realized exactly what it means to give everybody the means to be their own publisher.
I think there probably is a lot more porn being produced on a per-person basis. We have a lot more cameras and a lot more ways to share photos/videos now.
I think there is a lot more content in general being produced too.