Earlier quoted context omitted.
To reinforce your point, see all pre-modern crypto techniques. It cannot be argued that they worked, and they were all certainly security through obscurity.
Aren't most examples things where it didn't work? The most famous case is the German "Engima" device from WWII (hardware- and 'software'-based, but cracked and readable for years before the Germans knew because they believed it was both obscure and effective) but it's wholly possible that most schemes were broken eventually. Keeping an obscure system secret is really hard, especially against a motivated attacker.
It's also quite interesting to see that the Polish cryptanalists were able to reproduce the enigma machine used by the german army without even having seen one. They were able to deduce the number of rotors, the wiring, etc.
What in the end doomed the Enigma was the fact it was more a kitchen recipe than cryptography based on solid principles. It was a smart recipe for the time, but it had flaws (like the fact a letter could not be the same letter once encrypted). In some regards, most of our symetric encryption algorithms today feel a bit that way (with a lot more external scrutiny from experts however).
Even in WWII, I don't think that security through obscurity was considered as an absolute barrier. It's more in line with a "defense in depth" pattern. It gives a little more work to your adversary as he now has to figure out how your encryption works before breaking it, but it's not expected to last for long.