I was just reading a really long web page (a list of smartphones compatible with LineageOs) and needed to go farer without knowing exactly where or when I'll need to stop — since I was looking for multiple devices my family has. I didn't want to use the mouse wheel because the distance to cover was too great, and also because of its jerky behavior. Without mentionning leaving my eyes of the list counterintuitive.
I moved the mouse to the scroll bar without watching and luckily grabbed the bar. This is what I need: a scrollbar I don't need to look at to be able to reach it, no more hard to grab bar, and no more cursor ending on the top or bottom of the screen — the cursor stays where I clicked on the scroll bar.