> Only levels of obscurity exist
That's the good point. Looks like you're coming from some unusual recontextualization of the vague term "obscurity".
The way you initially stated it looked to many of us like "all obscurity levels are adequate security for a security-critical project" and I hope that's not what you meant.
Traditionally we distinguish these levels by not calling some of them obscurity at all.
These categories are distinct for a purpose; they have different properties. Steganography and obfuscation make systems harder to study and maintain. That doesn't happen if you increase some PoW requirement, for example.
Both make systems harder to break, yet one of them is less effective; it's useful only due to a synergy of combining both.