Frame generation is for when you can play at native 60 FPS but want more. More native frames don’t give you less noticeable input lag. But more (fake) frames still feel smoother. That’s the sweet spot for frame gen: playing at 120 FPS when your card can only do a little more than 60 FPS native (some native frames are sacrificed to the AI gods to get the fake frames to interleave with the real ones).
The advertising is ridiculous though.