yeah the "distance between frames" latency is just one overhead, everything adds up until you get real latency. 10ms for your wireless mouse then 3ms for your I/O hardware then 5ms for the game engine to process your input then 20ms for the graphics pipeline and so on and on.
30 FPS is 33.33333 MS
60 FPS is 16.66666 MS
90 FPS is 11.11111 MS
120 FPS is 8.333333 MS
140 FPS is 7.142857 MS
144 FPS is 6.944444 MS
180 FPS is 5.555555 MS
240 FPS is 4.166666 MS
Going from 30fps to 120fps is 25ms which is totally 100% noticeable even for layman (I actually tested this with my girlfriend, she could tell between 60fps and 120fps as well), but these generated frames from DLSS don't help with this latency _at all_.
Although the nVidia Reflex technology can help with this kind of latency in some situations in some non quantifiable ways.
if you added 200ms latency to your mouse inputs, you’d throw your computer out the of the window pretty quickly.