Could you explain if this was sort of an "aside continuation" re. the leetspeak comment or about encryption in general? In other words, are you saying that it doesn't help to add an "underlying" layer of additional encryption, or that encryption, in general, doesn't doe anyone much good?

First, just to make clear, those were separate events, far removed in space and time. Ciphergoth's remark was not directed at my leetspeak idea, but the principle applies just the same.

Encryption does accomplish the goal of raising the cost of accessing your messages to the point of infeasibility, and I wasn't trying to deny that. To expand on the point about the underlying encryption: generally, the published cipher you use to encrypt your data is far stronger than it needs to be to keep your data safe; any succesful method of attacking it would go after the implementation of it, and in particular the people that need to make it work. Hence this comic.

So let's look at your idea. Another relevant weakpoint of a cryptosystem would be the difficulty for the user of not messing it up, and this critically relies on you being able to access your (full) key. If you have to simultaneously do the work of remembering this secret language, this can mentally exhaust you and increase your rate of error in implementing the protocol -- so it adds a weakness to the weakest part of the system (the human) just to strengthen the part that's already the strongest (the encryption itself).

Does that make sense?