Well, you said "encrypt", what do you mean by encrypt? What's the key? In the Freenet's solution, they encryption key for the data is the data, not any random or user provided key. So the same plaintext is always turned in to same ciphertext. Which we all know, it's very bad idea, it ruins encryption. In this case, it's quite easy to spot out all of the users having the same content in their account.

This is only reasonable method when ever you can assume that every plaintext is unique, which also makes point of deduplicationg data absolutely pointess.