w/e, I think that's inaccurate. No biggie, I'll look into it.
EDIT:
Actually, you said it right there yourself... #1 reason = emissions. First and foremost it's an emissions device. Yes, by controlling it better you can reduce temps enough to advance timing even further and even further reduce emissions, BUT when the system was introduced that wasn't as big of a factor as they couldn't control it as accurately or readily. Emissions reduction though temperature reduction is the #1 reason. Yes, detonation control allows us to take it further, no argument... that's just not the primary reason for it being in the car.