So does your TV, if you have it switched on next to your laptop.
The real issue is where the content comes from. The browser doesn't provide a document - it's a dumb conduit for the page you're after. Whether you paid for your browser (Windows) or it's ad supported is irrelevant since it is itself incapable of copyright infringement. This isn't true of Scribd.
I do, because I like offering web sites I enjoy a chance to make money off me, and because I actually feel slightly empty when I go to a site designed around a Deck ad and don't see it. Tasteful ads make a web site look better.
