Those seats probably weren't broken intentionally. Just to give a bit of context, at Wanderers games the active support stand on their chairs to watch games. Alot of the chants that the Wanderers fans do involve jumping up and down, so you can imagine how, what's depicted in that pic, could happen when you have a full row of people jumping up and down, while chanting, on their chairs.
I know it doesn't look good, just wanted to add some context. Make of it what you will. I actually saw some people accidentally break their chairs while doing the Poznan (which is something that involves jumping up and down).