All address commercial email. The Murkowski Bill. The Torricelli Bill. There's some fear that it would give IETF decisions in this area the force of law. Spammers fake addresses regularly, use different providers, and change their messages around precisely to evade filters.
Broader filters can catch more spam, but they begin to catch nonspam as well.
This might give people the idea that there are places from which the content of the Internet can be controlled. The Whole World Looks to the US for Guidance Spam started out as an American problem. The big spam houses are all US-based. Our neighbors on the Internet want us to stop dumping our trash all over them, and the US needs to set an example for the rest of the world on how to deal with Internet governance. The fundamental problem with spam is that it imposes on recipients costs that they cannot recover.