For those who are not terribly in 'the know' about onion services, I can think of a few reasons why the CIA would benefit from operating a public onion site:
* Onions are more secure as they do not rely on x509/certificate authorities and DNS
* Visitor privacy
* Ability to research the traffic going to their site. They could probably learn patterns from it.
Also, in recent years onions have become also appropriate for "clearnet" sites. There is a config option for Tor to disable server-side privacy, keeping the visitors anonymous but speeding up the connection by reducing the server's hops.
* Onions are more secure as they do not rely on x509/certificate authorities and DNS
* Visitor privacy
* Ability to research the traffic going to their site. They could probably learn patterns from it.
Also, in recent years onions have become also appropriate for "clearnet" sites. There is a config option for Tor to disable server-side privacy, keeping the visitors anonymous but speeding up the connection by reducing the server's hops.