They would say that but the ratings are supposed to reflect default risk, not inflation risk and the ratings are not supposed to be a way of scold bad governments unless the bad governments are creating default risk. If US government debt is not AAA then 95% of the AAA rated corporate debt is also not AAA and should be downgraded. There has alway been a bizarre double standard between the way S&P, Moody's and Fitch rate municipal bonds compared to how they rate corporate bonds. In observable history lower rated municipal bonds have substantially less default risk then higher rated corporate bonds. I have not heard and explanation for why the ratings agencies rate some municipal bonds irrationally low. I guess the reason why the ratings agencies rate some corporate bonds irrationally high is because those corporations are paying the ratings agencies. I read an article that said the ratings agencies stopped being competent in about 1990.