I don't agree with that, you can get just as good performance with a carb as with FI, the carb is just not as EFFICIENT as FI. I remember some time back one of the car magazines did a dyno test on an engine using both FI and a carb. When tuned to the best numbers there was virtually no difference in the horsepower or torque ratings! Now if I could remember what magazine it was! Methinks I read too durn many magazines.
FI provides more accurate fuel metering/delivery as well as more precise ignition timing so although I have no figures to prove it, I would expect power gains to go along with that.
It also takes alot more time/skill to get a carb tuned to max effiency and I bet that the majority of mechanics the average guy takes his car to for a tune up comes no where near it. Not only that, when you do find your engines sweet spot with FI, it doesn't lose it.