OK, that info is a little old. A drivers license cannot be used to prove citizenship and the US State Department has stated as much. Even “closed loop” trips, such as a cruise to the bahamas or the caribbean, require a birth certificate at a minimum.
It's pretty easy to get back in the US. With or without ID. Ask 15 million illegal aliens.
So why do citizens have to jump through hoops? And bust the Constitution in the process?
I won't ever travel abroad again, since I don't study war no more, but I still have use for an intact Constitution.
/johnny