Historically, porn has had a limit. The possessor of porn only had access to so much novelty and variety. However, online porn creates an environment of endless variety. For men, this creates what some have called The Harem Illusion – the illusion of a never ending supply of new mates.
The dopamine reward circuit in the human brain is designed for a context of scarcity rather than abundance. Historically, access to new naked females in a context of mating was a rare event. The male brain is built to take note and to take advantage of this rare event by finding opportunities to mate. The male brain becomes singly focused on this opportunity.
Online porn stimulates this dopamine reward circuit in a context of abundance (as opposed to its natural environment of scarcity): the illusion of a never ending supply of new mates. Men receive pleasure from porn for precisely this reason: it stimulates us with that rewarding feeling that tell us to “go forth and mate” Biologically, males are built to spread their seed as far and wide as possible. Online porn creates the illusion of infinite opportunity for human males.
So that’s the fundamental difference between traditional porn and online porn: the binge mechanism, which triggers the organism to take advantage when resources are plentiful (because in our natural environment they are scarce), finds in online porn a never ending supply of new physically attractive women available, at least visually, in a sexual context. With traditional porn there was usually a limit to the supply.