Earlier quoted context omitted.
Again this is based on the same logic that people will treat the U.S. Government the same way they'd treat any other person and that's just not going to happen. If the U.S. falls back into recession we'll take everyone with us. Other countries know this. Banks know this. Institutional Investors know this. Increase the interest rate on the U.S. and you'll trigger an increase on the U.S. consumer while exacerbating the…
Some institutions are obligated (by charter or contract) to only buy AAA rated bonds. That's why it's a big deal... Now that being said, I have no idea how this would work in practice.
The whole point of a rating agency is to provide you with research that you couldn't get based on your available resources. But every economist in the world is a resource on the U.S. Government's viability. You can turn on CNBC and get 24 hour coverage of it.
So the U.S. is a special case and the ratings agencies don't mean all that much in regards to it.