Yes, scribd is probably within the law, but they are acting in a manner that I find immoral, and I'm not the only one.
The upshot, as so many others have observed, is that copyright law is a mess, as is patent law. Completely absolving vehicles for theft such as scribd from any form of liability is wrong.
However, the law has never been about right and wrong, so it won't start now. I've largely stopped writing now, concentrating on personal appearances. That at least turns a tidy profit, and is difficult to duplicate without my knowledge. My other company relies on commercial secrets rather than paying through the nose to divulge secrets, only subsequently to have to pay to find if they're stolen, then pay again to defend them.
With regards scribd and its ilk, I know I won't get my way. Morals can't be policed, because laws will always be gamed. I don't like it, but I'll have to accept it. I just won't play. Apart from continuing to check for infringements I won't use their site. It's an old-fashioned view, but quite simply, it makes me feel grubby.