I see what you're getting at, but you're missing that not everyone can be a specialist at libinput development, someone might spend his day developing software

I see what you're getting at, but you're missing that not everyone can be a specialist at libinput development, someone might spend his day developing software for 3D rendering, someone else is a data scientist, a third one designs websites. It makes more sense that each one spends his time doing what he does well instead of spending 4 hours figuring out how to modify libinput.