What do you think they should have done? Demanded to see ids of everybody trying to post an ad in their massage or escort sections?
Just how much human interactions do you think free ad sites have with each individual posting an ad?
Ummm … ya. That would have actually been a really good idea. Granted, there are a million ways around it but if they'd been able to demonstrate that they had been willing to engage in a measure of due diligence and try and provide a way to at least try and distinguish between legitimate advertising and the raping of underaged sex slaves, it would likely have substantially helped their case. They did know in advance that a certain percentage of their ads were for the raping of underaged sex slaves and that this exposed them to legal and financial jeopardy and yet did nothing about it. If they'd been able to point to such efforts to be able to tell legislators that they're on their side on this matter and are doing their part to have their site not associated with this aspect of the industry, there's a much better chance that they'd still be around.
It's like the porn sites which say that you have to be about 18 to enter and you totally shouldn't hit the Enter button if you're under 18. It doesn't stop any underaged people from accessing porn, but it at least allows them to say that they acknowledge the issue and don't support it.