That's a fair point, but you can say the same for OC with regards to distraction. My issue with the original statement is that CCR fatalities receive more analysis and there's more focus on the unit and operator/unit interaction. It's easier to make a determination of casual factors in a lot of cases. Distracted diver, malfunctioning unit, etc, if the loop went hypoxic, we can make at least a partial determination of cause. You can really only speculate if narcosis played a meaningful role.
With OC, assuming the dive was planned correctly (right gas(es) for that depth), the only thing you need to worry about is monitoring the amount of gas left (and turning it on before jumping in).
With CCR, the oxygen levels change all the time and need much closer monitoring. Lost count of the number of times I've read about someone who's died of hypoxia due to not monitoring their O2 levels, especially at the beginning of a dive and during descent.
I treat my box as if it's trying to kill me in some subtle way so cunning that a bald, fat geezer stroking a fluffy cat would be happy with. Damn, sharks with lasers, didn't see that coming...