Your information is very out of date. The old synaptics driver worked as you describe (implementing kinetic scrolling at the driver level) Libinput (which all

Your information is very out of date. The old synaptics driver worked as you describe (implementing kinetic scrolling at the driver level) Libinput (which all modern distros switched to ages ago) does NOT implement kinetic scrolling at the driver level. Instead libinput implements 'scroll sources' and it's up to the toolkits/clients to use that data to perform kinetic scrolling.