If this was MacOS, I'd agree. But on Linux, it's a different hardware landscape. There are hundreds of trackpads that Linux is compatible with, but not every one of them is multitouch (or implements multitouch the same way). Gesture support on Linux has been a long time coming, but that's mostly because getting uniform trackpad support over thousands of laptops is just not a very fast process, whereas on MacOS, Apple can make certain assumptions about the hardware it's running.
This makes it a lot more likely that apps are going to recognize that signal so it works for every system. It’s the paradox of choice.
That's not true. On macOS (and also iOS), you subscribe to gesture recognizers (i.e. swipe gestures), not isolated events, which give you easy access to how users interact with macOS without having to analyze (and likely analyze incorrectly) low-level trackpad interaction.
You could always choose to look directly at events instead, but if you are trying to get the behavior of a widely-used gesture like swiping forward/back, you will get much more accuracy (and happiness from users, and less dev time) by just recognizing them at a high level, which is what Apple expects.
In Windows and Linux clicking the trackpad with 3 fingers causes a middle click, in MacOS this is not an option at all. Moreover, enabling it is apparently a project so difficult that the cheapest solution[0] I could find costs €8 just to add middle click functionality, nothing else.
But thanks for the link, I'll check it out