Moody's, S&P and others slapped investment grade ratings on junk-filled securitized paper because that was their jobs: they were literally paid to do so by issuers and underwriters. Underwriters found they could shop for triple AAA ratings – if Moody's refused to provide a desired rating, then S&P would (and vice versa). When it all went south, the CRAs made feeble attempts to claim these business transactions as "protected political speech" under the First Amendment. These arguments failed, eventually leading to fines for their malfeasance.