Problem certain UI components need to react to mouse wheel or scroll events, but only as long as those are reflecting the direct user input.
The fact browsers/os also adds momentum scrolling to those events without any possibility to distinguish between these events coming from the system and those coming directly from the user makes it hard to write these UI components.
See the related discussion on Additional use cases for InputDeviceCapabilities - unfortunately it seems that the differences in the underlying OSes and hardware makes this unlikely.
Thanks for your answer. Something that I don’t understand than is that FF, Edge and partially Safari have implemented and Chrome is implementing CSS snap points. At least in combination with scroll-behavior: smooth. The browser somehow has to take over the scroll animation as soon as the user stops scrolling.
If you open the following site in FF: http://keithclark.co.uk/articles/practical-css-parallax/scroll-snap/ you see that FF knows when the user stops scrolling.
As an alternative touch like events for the trackpad would also help a lot.