Really? How so? I just checked, and there is a class of society called "The Feds", they were the "remnants of the US gov't federal system" and they did maintain they were a separate legal entity. Hows' my reading of the book different from yours?
The cool thing in the book was that you could opt out of US government protection, choosing instead to live in an enclave with services provided by some private party.
IIRC, Stephenson presented it as a bit dystopic, but it sounded quite exciting to me.
It wasn't opt out. The US Federal government didn't exist. Hence the regions of the book where a guy working for the Mafia is noticing the pings of bullets bouncing off his car as he drives through a rough neighborhood, and idly wonders whether the stains on the road are people who've been smeared into nothingness.
It sounds exciting because you're not living it right now. And in the modern world, it is surprisingly easy to recreate that experience - just the cost of an airfare.