That's the timing attacks I was talking about. Again, you keep everything in network on hidden services. Afaik, the onion routing's layers keep everything moving and untrackable within that space. They would have to directly infiltrate the host they want or have a backdoor that still hasn't been found... After what, 20 years now?
Plus, the more people that do use it, the less possible the timing attacks become on data that does leave the network.
We all know what Kevin Spacey did.