Earlier quoted context omitted.
You were alive three years ago; no? AIG, "AAA" rated CDOs, any of that ringing a bell?
You weren't paying attention. The ratings were issued by companies that had been given a monopoly by govt. Securitized mortgages were a creation of govt. The idea that you're missing is regulatory capture combined with govt encouraging transactions that didn't make economic sense otherwise. (One of the underappreciated consequences of RC is that it amplifies "private" bad behavior and shuts out good behavior.)
The government didn't corrupt Moody's. Commerce did. The government supplied no oversight, and Moody's sold its ratings to the highest bidder.