The difference is that Pearl Jam has been pretty openly left wing for quite some time. Those who are their fans don't mind this even if they may not agree with them. For instance I love listening to Pearl Jam or Rage Against the Machine even though I am on the polar opposite side.

I think the issue with the Dixie Chicks was that their image wasn't as rebel but as mainstream patriotic country singer. Further people who listen to country music are far less accomodating of what they perceive as unpatriotic acts.

In rock music we all recognize that half of them are junkies and insane. We just love the music. Anyone who takes a rock musician seriously is probably in need of some counseling themselves.

One exception might be Bono. Say what you will about him, I think he went about his advocacy the right way. He even got a lot of conservatives like Orin Hatch on board. I disagree with him on some issues, but he actually got informed and made persuasive rational arguments. Contrast this with the typical stuff coming from Rage's frontman or the comments Eddie Vedder has made.