The very first answer to the question you posted seems to disagree. They poster basically points out that when people say "security through obscurity" they don't mean passwords. Well, of course they don't or they'd realize that security by obscurity is valid and used successfully every day. You just need more than one layer of protection. Passwords alone aren't enough, trying to obscure the port number of your service isn't enough, etc.
By your definition basically all computer security is security through obscurity. After all, crypto keys are really just obscure numbers that could be guessed.
The only exception would be an air gapped network. But wait, what if someone figured out the passcodes and physical keys to enter the building?!
You already said you were ok with "security through obscurity" when you logged in with a password.