Sometimes, it doesn't take a whole lot of effort to do something for a stranger, and when that something is moving your mass a few feet in either direction to allow someone else to share access to something that everyone there specifically came to see… you're socially expected to do so. No one owns a public space or viewpoint of desirable scenery—that's kind of the point—and while they don't have an expressed claim to that location at that given time, neither do you have the right to block it f…