I'm left wondering -- isn't this a toolkit/library issue?

I am a bit afraid of seeing gestures handled differently in multiple programs, like inertial scrolling, or pinch-to-zoom speed. At least gestures are always detected by libinput AFAIK, so there's that.

But instead of implementing this in every application, wouldn't it be nicer to implement the common part in a library and link that library to all app that require/want touch handling? This would provide homogeneous behavior, and would allow sharing configuration files.