The tactile feedback comes from the fact Mac OS has the concept of a scroll having an amount of inertia behind it, if I very gently move two fingers up and down

The tactile feedback comes from the fact Mac OS has the concept of a scroll having an amount of inertia behind it, if I very gently move two fingers up and down on a long web page then it will very gently move a few pixels, but if I flick two fingers from the bottom of the touchpad to the top then its going to go flying upwards. If I then put a finger down on the touchpad it'll stop the scroll immediately. This behaviour one of the things in Mac OS that nobody really notices because it feels so intuitive, but if you took it away everyone would be puzzling over why scrolling feels broken.