Comment 2 for bug 1698132

@Cristian (vmman)
It is called natural because if you push your finger on the mouse wheel UP, whats on the screen moves UP. Just like if you had a piece of paper on a table, if you pushed it UP, and it moved DOWN, that would be a very strange experience!

It is a more direct approach as it removes any in-between device such as a scroll bar, or pseudo-viewport. It's just your finger and the content. The same is standard on a tablet or smartphone.

This behaviour is particularly important for people who do visual tasks such as drawing, photography and design. Where you are just as likely to scroll left-right, diagonally and even in a curve. When scrolling reveals more of the content, the user is likely to need to change the scrolling direction during the operation. Thus a curved direction. It is less important for people who just scroll text up and only have simple interactions.