This! It's about being considerate of the hoards of people SLEEPING around you. Simple!
Even when you get up early to go fishing for example, you try to keep your noise to a minimum because the majority of the camp ground is still asleep.
I think 6.30/7.00 is acceptable in a camp ground because you do usually get up early. But I think you generally go with the flow - if campers around you are rising at 6am, you're going to wake up then too. If there is just one screeching group of campers waking everyone up -well then that's not fair.