Dangers of rope worn carabiners

Interesting test of worn carabiners by Black Diamond via ACC NewsNet

Although nowhere near as bad as the ones shown here, I recently retired a number of old biners when I noticed they were showing distinct grooving (probably from top roping). I retired them out of general principle - I never even thought of the danger of sharp edges cutting the rope. 

I'm always distressed by how people continue to use ropes and harnesses and other gear long after it should have been retired. There are always excuses, but do you really want to take chances with something like that?