On older systems, scrolling on the trackpad would emulate mouse scroll wheel events - scrolling my one (or more) lines per increment.

This made sense with scroll wheels, because they moved in discrete (large) clicks.

The problem isn't capturing one-pixel accuracy with the trackpad deiver, it's that at the application layer a lot of legacy mouse input APIs treat scrolling as if the user still has a 90s-era mouse with a physical scroll wheel.