I agree with everything you've said about the path this country has taken since FDR, but that misses the whole point of a credit rating. What other credit instruments since the 1930s have outperformed U.S. Treasury bills in terms of safety and reliability? Government bonds from Nazi Gerrmany? Japanese bonds from the Hirohito regime? Corporate bonds issued by General Motors?
Keynesian economics corrupted much of the Western World. So, no, most of the major national debt offerings since the 1930 have been even worse investments than U. S, Bills & Bonds. There are exceptions, of course. Any Swiss Franc denominated obligation, for the obvious. The Swiss Franc at one time was worth 20 cents (U.S.). It has lately been worth well over a dollar. The dollar is now worth only about 77% of a Swiss Franc. Whose bond would you rather cash in?
Now there are bonds that have guarantees against currency devaluation. But the history of such is suspect. When they are really needed, they may not function as promised. When FDR devalued the $ from 1/20.67 ounces of gold to 1/35 ounces of gold; he also repudiated the gold clauses in such bonds. And one of the most tragic of the many terrible 20th Century Supreme Court cases, was the one where by a 5 to 4 vote, they allowed FDR to get away with it.
William Flax