[kwhitefoot]

> in a printed book, it is easier to find a previous page and compare a fragment on it with the current fragment.

This is why I like plain text for everything (or Emacs Org Mode) because then I can have multiple frames showing different parts of the same buffer in Emacs.

[medstrom]

You can also create several browser tabs visiting the same page. Of course, no one thinks to do that.

[davegauer]

Make that several browser windows. And that's a good point. I sometimes end up inefficiently scrolling up and down a document to reference different parts of it. It almost never occurs to me to open another browser window with the same page for side-by-side reference.