I think it is directly related to ebooks, in fact this is precisely why I bought an ebook reader. I used to print off academic journal articles, essays, book chapters etc. and carry them around in lever arch files, which became increasingly disorganised the longer I had them. Now everything gets put into folders on my reader and it organises itself on the basis of the metadata in the individual files.
I used to buy a box of paper (that's 2500 sheets!) every couple of months. I haven't bought a box for at least three months and there are still more than three reams left of the last box I bought.
I find I still need to do final proofing of my own stuff from hard copy though - but that is possibly just some kind of "hand over anxiety" on my part - at some level I still believe that if I haven't seen what I produce printed I can't really sign off on it. But I'm getting there!