It's not that different, as Comiket is first and foremost a marketplace. The popular publishing circles sell out quickly, so people are motivated to line up early in order to get what they want.
Their FAQ mentions that if you come on the first train, you'll have to wait for 5 hours, but if you come at the opening time of 10:00, you only have to wait approximately one hour. The fact that people are willing to spend those extra 4 hours to get in early seems to indicate that it provides an advantage to be one of the first.
Incidentally, they expressly prohibit waiting in line overnight. I bet plenty of people would do so if they could.