Why?

I don't understand it. I know a lot of people make fun of guys that do this. Normally I wouldn't care, but when I'm in the gym, and it's crowded, and I'm waiting for the squat rack because it's being used by some guy doing curls in it, it does kind of p*** me off too. It happened to me yesterday. Some guy was standing there at the squat rack talking to one of his buddies for like 10 minutes, while I stood there and patiently waited to get on there. He noticed that I was waiting, and he apologized and told me that he only had 1 set left. He then went on to do his last set, which happened to be a set of curls. I was a bit annoyed.

Is it different then using the EZ bar? Is it beneficial in any way at all?