FT seems not to want to see the forest because of the trees.
You write it is ”meaningless to say that the ratings agencies were wrong in hindsight – the question is whether they made responsible use of the data they had in 2006 or early 2007”. Hold it there! This is not a question of given points for performance or style in a high jump contest. The credit ratings were empowered by the regulators to impose on the market their criteria not because they were going to responsibly use any specific methodology but because they were supposed to be right! If they cannot be right...who cares about whether they act responsibly or not... we do not need them...in fact the more credible they are the more the dangers that we will follow them where we should not.
Yes I do blame the credit rating agencies, who should as a bare minimum inspected a sample of the subprime mortgages offered as a collateral to see if they even belonged to the same universe of data they had before taking them as a good guarantee, but, much more do I blame the regulators who empowered the credit rating agencies to begin with and thereby set us up to extremely dangerous systemic risks.