Kerckhoff's Principle specifically applies to cryptosystems. Not only does TFA describe more of a generalized application to systems and code, but it's not really describing 'security through obscurity.' It's describing informational arbitrage, i.e., profiting (not necessarily financially) from an imbalance of knowledge on one side of a two-participant game.
The dynamic adaptive approach has its merits, particularly as it is increasingly clear that most security is only the illusion of security, maintained until it is breached. But traditional 'security through obscurity' refers to systems for which the only security measure in place is maintaining the secrecy of a protocol, algorithm, etc.
It seems to me the ideal approach is a balanced one, that embraces the UNIX philosophy: cover the 90% of most common attack vectors with proven security measures (and update practices as needed), and take a dynamic adaptive approach to the edge cases, because those are the ones most likely to breach if you've done the first 90% correctly.