It's not paper books that become obsolete, but paper tech books. Although I love paper books and will never stop preferring them, they're less good for timely technical material like 'how to' books, which do go out of date.
That said, not everyone has a Kindle or a tablet, and if you're trying to do something difficult on the computer (true by definition, if you're using a 'x for dummies' book), then you don't want the tutorial material on the same screen as the software you're trying to wrap your head around. Also, I don't think they'll be obsolete in a year, more like 5+. Indeed, I've found that buying cheap books on complex software that go a few editions back is often an equally good way to get a grip on the fundamental skills even if the interface has changed in the meantime - you can easily figure out the newer features later, whereas learning the shiny new stuff first can often delay getting a good grasp on the fundamental skills.
> It's not paper books that become obsolete, but paper tech books.
Yes, exactly. Maybe I haven't articulated my point in a clear enough way, but I meant only paper tech books, and not all of them, but the ones about topics that change fast enough to make the book obsolete soon after being printed.
I have a paper copy of SICP, which is a quite old book, and yet it's probably not going to lose its value for next few decades. But books about, say, current most hip MVC JS framework get obsolete within a year from the date of publication. I'm hoping that the industry will move to print-on-demand tech books because as you said, there's a great value to having your documentation / tutorials somewhere else than on the screen (heck, I often print out RFCs when I need them for work), but dumping short-lived books on bookstores around the world just feels like a huge waste.
That said, not everyone has a Kindle or a tablet, and if you're trying to do something difficult on the computer (true by definition, if you're using a 'x for dummies' book), then you don't want the tutorial material on the same screen as the software you're trying to wrap your head around. Also, I don't think they'll be obsolete in a year, more like 5+. Indeed, I've found that buying cheap books on complex software that go a few editions back is often an equally good way to get a grip on the fundamental skills even if the interface has changed in the meantime - you can easily figure out the newer features later, whereas learning the shiny new stuff first can often delay getting a good grasp on the fundamental skills.