> Somehow I can't see an internet mob ganging up on someone who remixed a song (of an indie artist) and refused to see anything wrong with it.

It is a blend of the fact that the remixer was trying to make money off of the stolen content, and that the original writer had specifically told them to stop (which the remixer refused). I think it also sort of plays into people's underdog complex a bit, or wanting to stick up for the 'little guy'.