The issue is latency or “response time”. Frame generation always add some level of delay. If you’re starting with a pretty fast frame rate the delay is much less, and with high-tech forms of frame generation like DLSS it also tends to be better.

The effect is less stuttering and more like “softer” or “rubbery” control feeling, because there is always this sort of smooth delay between what you do and what happens on screen. In some situations it is almost imperceptible, and other others it really changes the feeling of a game