That doesn't absolve anyone of responsibility in regard to the law. Whoever was in contact with them and suspected them could report them to the police. In most

That doesn't absolve anyone of responsibility in regard to the law. Whoever was in contact with them and suspected them could report them to the police. In most jurisdictions, witnessing a crime and not reporting it is also punishable. It simply prevents the over-zealous censorship that happens when you put all responsibility on a single actor (Tumblr, YouTube, ...).