This is the first I’m hearing of this law, but is the point that platforms are now responsible for policing whatever content they host? Does craigslist just not

This is the first I’m hearing of this law, but is the point that platforms are now responsible for policing whatever content they host? Does craigslist just not want to take on the burden of ensuring there’s no sex trafficking on its personals site? On the one hand that seems fair- but suppose craigslist is doing all it can to police its site, at a certain point criminals can outsmart them by using secret codes or other less obvious subversion tactics. At what point is it clear that a website is doing enough to police itself that it won’t be liable for criminals who are going to great lengths to outsmart them?