Yeah, I can agree that Antifa is doing the left a disservice. It's social activism for people who are too stupid or impatient to change the system the way that it's supposed to be changed in a democratic society. Plenty of the people out there throwing bricks and spraypainting stuff probably didn't even register to vote.
Can you blame them? There's certain stuff that just can't be done through our political system, because it's not in the interest of either party. For example, campaign finance reform or a voting system that isn't FPTP.