It's a barrier, too...even if not a real physical barrier, a psychological one.
Our house is on the corner and people are all the time cutting around the end of our garage and across our front yard. I've been startled pretty badly a couple of times, going out to my car, by someone just walking through my yard.
I've thought of putting up one of those decorative barrier type fences...but nahhhh...I'd just soon put about 5 acres between me and anyone else.