This is another writer I respect. Jakob Nielsen is a well respected web usability guru. He writes a monthly article on various aspects of the web. This is an article from 1997 about writing for the web. I used this article to help teach my students in Denmark.

Jakob Nielsen's Alertbox for March 15, 1997:

Be Succinct! (Writing for the Web)
The three main guidelines for writing for the Web are:
Be succinct: write no more than 50% of the text you would have used in a hardcopy publication
Write for scannability: don't require users to read long continuous blocks of text Use hypertext to split up long information into multiple pages

Short Texts
Reading from computer screens is about 25% slower than reading from paper. Even users who don't know this human factors research usually say that they feel unpleasant when reading online text. As a result, people don't want to read a lot of text from computer screens: you should write 50% less text and not just 25% less since it's not only a matter of reading speed but also a matter of feeling good. We also know that users don't like to scroll: one more reason to keep pages short.

The screen readability problem will be solved in the future, since screens with 300 dpi resolution have been invented and have been found to have as good readability as paper. High-resolution screens are currently too expensive (high-end monitors in commercial use have about 110 dpi), but will be available in a few years and common ten years from now.