Guest, graphics and text are no different from music, they're also covered by copyright. You have no more right to photocopy a magazine or download a photo than you have to download music. Similarly, putting a photo or poem by someone else on the internet is no different from posting someone's music (as those who put copyright lyrics on Mudcat sometimes have to be reminded).

Intellectual property of any kind is subject to copyright. And yes, the creator does have the right to sell it to someone else, but that's their choice to do so.

I suspect if you were to go on a photography forum and brag about downloading someone's photos from a free download site without the photographer's permission you'd get a similar response, but this is a music forum so we're discussing music.