Can obscurity make cryptography better?

I often disagree when the so-called experts talk about security in terms of binary decisions. Managing security risk is always a cost/benefit trade-off compared to the value of the thing being protected.

I have always been particularly bothered by security proponents who repeat the mantra, "Security by obscurity is no security," when that declaration is demonstrably incorrect. Obscurity does have value, sometimes significant value, especially in the context of the defense-in-depth paradigm. I've written several articles defending obscurity each year, both here and elsewhere. Even though I can present facts and numbers, and readily demonstrate repeatable experiments to back up my conclusions, my critics usually rely solely on emotional arguments. At the very least, they can never show me how obscurity decreases security without coming up with hyperbolic, unlikely scenarios. A friend shared a popular saying with me: "I can show you the facts, but never convince you."