Best short analogy: I play music by ear and hate learning "by rote". Quickly recalling things in great detail is not my forte, I need some context through ear or visually and that helps me to recall the details.
In the TrackMania case, if the context is delayed by latency, that shortens the actionable time, or opportunity to press the correct key in time. By context I mean, in TrackMania there are repeating elements in the track designs, so you learn one particular curve, and as other track authors use the same type of curve often, one just needs to recall is the timings for that curve, and time the actions as I see that curve approaching. This allows the play of relatively advanced and never seen before maps with high success rate (finishing the track on first attempt at full speed without crash). Some authors use custom tools to make track modifications not possible in the built in track editor to keep things fresh.