Of course it doesn't. But just like with other miracles, God in his goodness sometimes gives us to them anyway. Why would you want to cast aspersion on a possible gift from God?
Well said.
As I (think I) remember it, there was an exhibition of the Shroud in the 1930's. It was viewed by a young Hans Scholl, and was a factor in his decision to organize the White Rose resistance and actively oppose the Nazi regime. The Shroud made him reflect deeply on the power of Christ to overcome death.
People do respond to outward signs. That's why God provides them.