Having observed a fair amount of computer based primary school, it seems to me anyway that the biggest problem is that kids just can't focus properly that way. Even if the machine is locked down to prevent open internet access, it's just too easy for them to become distracted by the medium itself. Books, pencils and paper may not be flashy, but isn't that actually desirable, in this context?

Yup. As a kid I could "entertain" (distract is the better word) myself by "drawing shapes" with the cursor, highlighting random things, switching between random cells in Excel, or just like... browsing through the system without any plan or reason. Procrastination is hell of a drug.

I'm so lucky I didn't have this in the classroom.

People are saying, oh i used to doodle, blah blah. But doodling in the margins is very HELPFUL for the rest of your brain to focus and memorize what is happening in the lecture.

Even doodling on the margin can be distracting. Or doing little tricks with the pencil. But these don't distract the verbal part of the brain as much perhaps.

I was on the tail end of no-screen schools, and even then I could find anything to distract myself with, daydreaming if necessary. But mostly doodling the gutters.

If you open any of my middle school notebooks you'll find around 5-10x more doodles than notes, by surface area.

It's arguably LESS distracting, since you can lock down the available actions on a Chromebook, for example, while I was doodling away in my notebooks as a 90's kid. I don't think you can really make sweeping statements about which is better overall.