I get the principle of the point you’re making but I don’t see how it can work if (and maybe this is the key bit) a state is allowed to have secrets.

Perhaps I’m blinkered, but I can’t see how a modern state can function without them in some form. To offer an extreme example, nuclear launch codes must remain secret. (Separate argument obvs about the merits for and against nuclear weapons).

If the state is going to have some secrets, I don’t see how they can work in practice if everyone is allowed to know them.

Separately I’m not sure I buy the slippery slope argument as an absolute given. It’s a clear risk yes, but I see good journalism as one of the safeguards against all forms of government malpractice, corruption or straight incompetence.