The titles aren't encrypted. Perhaps people are putting personal data in the titles of their posts, or hinting at personal data in the encrypted portion? Which

The titles aren't encrypted. Perhaps people are putting personal data in the titles of their posts, or hinting at personal data in the encrypted portion? Which is still a problem since the code served by the site has access to the plaintext, even if it's not normally sent back to the server. It would be trivial to change the code to send the plaintext or encryption key to the server, or just weaken the encryption somehow. Even if you trust the site operators they could be ordered to implement a change like that with an NSL, and prohibited from talking about it. As they say in the FAQ, the encryption is there to provide plausible deniability for the operator of the site, not to protect the users' data.