So far I only met trackpad magic/mouse scrolling on a mac or laptop. That leaves a lot of desktop computers out.
I am typing this on a iMac 2006 and even if the mouse has a wheel I still grab the bar because it's more precise (it allows to put the text where I want) than scrolling (which just increments height offset by a proportional fixed value).
When my mouse died, I got a magic trackpad instead. It's much more precise than using a mouse, you don't need to keep hunting the scroll bar everytime you scroll, and with all the gestures I don't even miss the mouse anymore. With a little practice I'm even able to do Photoshop work from the trackpad.
I am typing this on a iMac 2006 and even if the mouse has a wheel I still grab the bar because it's more precise (it allows to put the text where I want) than scrolling (which just increments height offset by a proportional fixed value).