I didn’t understand it back then, and I still don’t today. I agree, reading from paper is much better than reading from a screen. BUT. Reading websites from paper doesn’t seem to make any logical sense. Books, yes. Websites, no. I also think separate CSS files for printing is the way to go, over a PDF version of a site (just saying that seems wrong). PDF’s are so final and static—not what most of today’s websites are going for.
Don’t get me wrong, I think PDF’s have a very valid place. Especially concerning eBooks, documentation, references, 4+ page articles, etc, but I don’t think anyone can say they get excited when they click a link only to have the browser freeze up for 15 seconds while a PDF opens. Usually I’m just waiting for it to finish so I can close it. If it’s a one-time deal that’s one thing, but having wanting to download a PDF to read a site is entirely different—that’s way too much work. It’s borderline ridiculous (to me, anyway). Personally, I hope we don’t see the ‘prefer reading from paper?’ buttons showing up on more and more sites. And I would be surprised if that became a growing need.