There is a related essay in http://www.gnu.org/philosophy/my_doom.html.
No, they aren't. You're right.
But certain countries have an unacceptable history of internet fraud (statistically). So most online retailers block them from purchasing anything
(Romania, Nigeria, Pakistan, Zimbabwe, Ukraine, Bangladesh)
If any of these countries started using bitcoins for their online purchases, everyone would ship there. Since bitcoins can't be reversed in any possible way, the seller is 100% protected against fraud,
and scammers are unlikely to purchase anything because they realize they can't cheat the seller.