On that level, the danger these sites pose isn't so much moral corruption as boredom. This consolidation risks deadening the online porn industry. Essentially, the majority of porn sites are clones. Search engine placement is everything. This is an important marketing innovation, but in terms of quality of user experience, the results are still deadly dull.
Porn sites tell uninspiring narratives.
Their art is in their software engineering. It's well known among adult industry marketers that porn aficionados continually require fresh content. The topics they cover haven't changed since Adam and Eve, but their technologies are impressive and indicative of where the web is going. For example, the visual and auditory ingenuity that progressive porn sites deliver presages favorable developments in the mainstream. Given how many users they serve, the scalability and reliability of these sites is remarkable.