When I used to use the tie out cable and give my dogs access to the entire campsite, I had several instances when another dog came into my campsite and approached my dogs. I realized how easily something could happen when my dogs were 15 to 20 feet away from me. Once, I had 2 schnauzers stand just out of reach of my dogs and bark and pee. My dogs saw that for the aggressive stance it was meant to be and became more territorial of "their space" than before. By the end of the weekend, I was at my wit's end and my dogs were stressed out.
So, I stopped using the tie out. Now, my dogs have their personal space not territory. They don't feel the need to protect the space - they just protect themselves. I also don't have to constantly get up and go settle them down because they are right with me.
While I would love to be able to give my dogs more freedom, I have learned that I cannot trust other people to follow the rules or use common sense or courtesy. So, the only time my dogs are more than 6 feet away from me is when we are in an enclosed area with only dogs and people I know.
My other reason for that is because people are really stupid. I have had people walk right up to my dogs and hug them around the head and shoulders. If i'm 15-20 ft away, I can't get there quick enough to stop that. With them on a leash, as soon as someone starts approaching, I can reign my dogs in to me preventing the person from doing something assinine. And that prevents a dog bite that my dog will be blamed and punished for.