I may be a total cynic, but I would not be surprised that, if you dug deep enough, you'd find out that many of these 'activists' -however well-intentioned they may be - are being funded and encouraged by the very people they want to put behind bars.
If I were a sex-trafficker and knew or guessed what was going on with Craigslist or Backpage, I'd've wanted them shut down, and that's the way I'd have chosen to do it.
It's the same as the immense boost the pornography industry got in the 1970s from the campaigns of Lord Longford and Mary Whitehouse.