Especially since it works best at high frame rates. Like, if you were playing 30fps doubling to 60 might be a perceptable difference because of how long it is in between frames.
But going from 60 to 120, it’s still 50% “fake” frames, but the time between “real screens” is much smaller allowing for more frequent corrections to what the “fake” frames are predicting.
So while it won’t help a bad computer run anything, it can help a “mid” computer make what it can run look a lot better, because you can crank up a bunch of options to maintain the fps you were getting without I.