Looks silly, but I bet it's there so they can get a count of the people that use the path, If they forced you through it, people would be tempted to jump it, but by asking....likely on a sign we don't see in that picture...people are probably happy to turn it, for whatever cause it might benefit.
That's my unsolicited opinion of what it is. I wish we had a way to make friendly wagers on this board.