Although you can never completely eliminate it, technological fixes to do velocity checking, source IP address profiling, etc., seem so obvious I just don't see how this can be any sort of insurmountable problem...
Agreed but see bellow
It should have been obvious from the start that you would have a lot more people trying to steal service from a porn site than from, say, a Disney site.
I think the problem is that a large number of the people who run porn sites are neither technically sophisticated nor well funded. I suspect that many do not know how to write a program and can't afford hiring someone to do it for them. Its a business where there are low barriers to entry and there are a very large number of competitors. One way of discouraging new entrants is to claim that there are major technical problems... Phill