Why aren't Websites Listing Escorts Guilty of Facilitation

Or some other crime?  This MSNBC story on rating and contact sites for "escorts" is on thin ice, I would think, yet operates openly.  There may be some special federal statute or something that protects internet site operators in this context, but it would seem to constitute facilitation. See, e.g., this North Dakota statute: "12.1-06-02. Criminal facilitation 1. A person is guilty of criminal facilitation if he knowingly provides substantial assistance to a person intending to commit a felony and that person, in fact, commits the crime contemplated, or a like or related felony, employing the assistance so provided. The ready lawful availability from others of the goods or services provided by a defendant is a factor to be considered in determining whether or not his assistance was substantial. This section does not apply to a person who is either expressly or by implication made not accountable by the statute defining the felony facilitated or related statutes." [Jack Chin]