Is there a way to disable all scrolling online? (for desktop)
I think what you're most likely interested in is disabling a certain animation. 
I'm on Mojave, but the following command supposedly works since Mountain Lion (I tested it with Numbers and Safari):

defaults write -g NSScrollAnimationEnabled -bool NO


In case you don't know how to enter this: Open the Terminal application (it's in Applications - Utilities, or you just open it using Spotlight) and enter the command there. You will need to restart an application for it to have an effect (e.g. Safari won't only change behavior after you do that).

This should affect all applications unless the developers did some weird custom stuff to move around a scroll view.

What it does is, I think, exactly what you want: It disables the scrolling animation when you press the "PageUp" and "PageDown" buttons. 

Actually I guess it disables animations during scrolling in general, but when using the scroll wheel or the regular arrow keys the jumped distance is so small that subsequent jumps result in a "manual animation" anyways (animations are after all just a row of still images with small differences shown quickly one after another).