To me it just seems a more or less natural outcome of the major structural flaws in the whole business model. I’m not sure you need an explicit conspiracy for credit agencies to begin behaving in such a way that maximizes their revenue, it was mostly just a natural outcome of competition and extremely useless and inefficient regulation. If anyone deserves to go to prison it’s the people who were supposed to be regulating the banking industry.
Obviously the Federal government had zero interest in doing that but if they only went after the bankers it would have quickly become obvious that they are not the only ones to blame.