Um, cuz most peeps don't care about competition. Personally, I don't see the point of being at a con without a cosplay on, unless I'm sleeping...and even then, sometimes I fall asleep wearing one.
Anyway, people gather in groups, show their allegiance to particular series and take photos. I don't know...why does cosplay exist? What's so compelling? Why do I keep making complicated, huge and unfortunately hot costumes and swap up to three times a day? I think it's better not to question it, really.
...Altho: it was incredibly odd that there was no hallway judging it seems at ACen this year. It was not mentioned in the programming and no one on staff knew anything about it. The first time I was considering doing that ever, and ACen either didn't have one at all or did not advertise it well if they did.