He's using backend in the direct marketing sense... What you do with a customer after you make the initial sale (cross selling, up selling, follow up pitches, customer reactivation, referral drives, special events, etc, etc)
It's like seeing an article titled "Online Music Sales Drop" only to have 1/3 of it be about online movie sales. Yes they're related, no that doesn't mean it was a good title.
Fair enough. Craigslist posters aren't pornographers either (even according to the article they're engaged in prostitution, not pornography).
The writer shouldn't have spent 87 out of 312 words talking about an only tangentially related topic (do we really think that Pornographers No Longer Love The Web because craigslist stopped letting local prostitutes post ads?)
1. Craigslist is NOT a pornographer, so talking about the voluntary (and not for lack of users) removal of their adult section doesn't make sense.
2. I think we all understand that at any time some websites will be shrinking, if we're going to talk about pornographers as a whole let's see some statistics about pornographers as a whole.
3. I would be very interested to know which sites are growing and which are shrinking. My guess is that themed sites are loving all the piracy, because some percentage of customers will want to see more of the same. Random porn scrapyards are probably getting it the worst, because that's exactly what's being offered for free.