I'd agree with the idea that the majority of US TV comedy is rubbish. Seinfeld and Curb Your Enthusiasm are not counterexamples. CYE is not funny, at all, not once... I can't even identify where the jokes are meant to be. It's like some alternative-humour language I've never been taught a word of.
Arrested Development is - I'll grant - occasionally entertaining, but not quite the work of genius it's been made out to be.
Mind you, Archer has me in stiches, so I guess there's always some counterexample.
Except for Australian TV comedy, which is utterly and universally shite without exception. It's weird because Australians are some funny buggers, and their stand-up can be hilarious.
Sorry, rest of the world, but the UK still reigns supreme when it comes to the TV comedy (and particularly comedy-panel shows).