The interesting thing: Some Distributions have smooth scrolling (or interial scrolling / kinetic scrolling) by default (Fedora, Ubuntu) and some don't. Those who have enabled it, have no speed setting, so most of the time it's way to fast. I tinkered around a very long time with libinput-config to get it right and now it's acceptable. But it is still waaay better on macOS.
It is NOT a hardware issue though. I tried "hackintosh" on my T460s, and the touchpad experience is nearly as good as on a MacBook, so it is mostly software / OS.
Please don't perpetuate the awful terminological confusion around this issue.
Anyway, it's nice to have different settings that suit different people.
1) It's too fast. My Android phone also scrolls like XINPUT2 but it's got a smaller acceleration. But maybe it's what you say about getting used to it.
2) That would work in Firefox and every other window would still scroll in the other way. That's really bad and works against getting used to a specific scrolling behavior. I don't get it: the scrolling behavior should be managed at a level below every application. All the scrollbars should behave in only one way, except the random application that implements its own logic because of some important reason. So I would expect a system wide setting for XINPUT2 or traditional scrolling.
If you want it to not scroll further you need to stop scrolling before lifting you fingers. That should be pretty easy to get used to.
