Yes, but then you just have one hand on the keyboard. So now to type, you have to bring your right hand down, and resume typing. The distance there is greater vs. using the touchpad. I just have to flick my wrist and boom, I am on the touch pad scrolling. On Surface, assuming I hate the touchpad and want to use the screen, I have to take my hand off the keyboard, put it on the screen and start scrolling.

If having your hands on the keyboard is so important, on a Surface you can just scroll with the arrow keys, the way Flying Spaghetti Monster intended.

Screen scrolling is for those cases where you do not need to type. Which is actually a lot of online content consumption these days.

If you never do prolonged reading on your devices, then yes, it's not a scenario for you specifically. But many people find it quite useful.

Why do you assume that you have to use the screen or the touchpad exclusively? Surely if you're going to be fliting back and froth between keyboard and scrolling you'll use the touchpad but if you're reading a longer form article you rest your hand on the desk with your thumb on the screen and scroll comfortably. Both can work.